feat(apireference): Add support for nested types

Add support for nested types to generation of API reference.
Nested types will show up in the list of types and get a documentation page just like top-level types.
A list of nested types is included in documentation page of the surrounding type.

See PR #6

docs/demoprojects/api/DemoProject/DemoAttribute/index.md

@@ -7,7 +7,7 @@
 An example of an custom attribute class for methods
 
 ```csharp
-[AttributeUsage(AttributeTargets.Method | AttributeTargets.All)]
+[AttributeUsage(AttributeTargets.Method)]
 public class DemoAttribute : Attribute
 ```
 

docs/demoprojects/api/DemoProject/DemoPropertyAnnotationAttribute/index.md

@@ -7,7 +7,7 @@
 An example of a custom attribute that is used to annotate a property with custom flags.
 
 ```csharp
-[AttributeUsage(AttributeTargets.Property | AttributeTargets.All)]
+[AttributeUsage(AttributeTargets.Property)]
 public class DemoPropertyAnnotationAttribute : Attribute
 ```
 

docs/demoprojects/api/DemoProject/NestedTypesDemo/NestedClass1/constructors/index.md

@@ -0,0 +1,10 @@
+# NestedTypesDemo.NestedClass1 Constructors
+
+**Declaring Type:** [NestedTypesDemo.NestedClass1](../index.md)
+
+```csharp
+public NestedClass1();
+```
+___
+
+*Documentation generated by [MdDocs](https://github.com/ap0llo/mddocs)*

docs/demoprojects/api/DemoProject/NestedTypesDemo/NestedClass1/index.md

@@ -0,0 +1,25 @@
+# NestedTypesDemo.NestedClass1 Class
+
+**Declaring Type:** [NestedTypesDemo](../index.md)
+
+**Namespace:** [DemoProject](../../index.md)
+
+**Assembly:** DemoProject
+
+This is an example of a nested class
+
+```csharp
+public class NestedTypesDemo.NestedClass1
+```
+
+**Inheritance:** object → NestedTypesDemo.NestedClass1
+
+## Constructors
+
+| Name                                    | Description |
+| --------------------------------------- | ----------- |
+| [NestedClass1()](constructors/index.md) |             |
+
+___
+
+*Documentation generated by [MdDocs](https://github.com/ap0llo/mddocs)*

docs/demoprojects/api/DemoProject/NestedTypesDemo/NestedClass2/NestedClass3/constructors/index.md

@@ -0,0 +1,10 @@
+# NestedTypesDemo.NestedClass2.NestedClass3 Constructors
+
+**Declaring Type:** [NestedTypesDemo.NestedClass2.NestedClass3](../index.md)
+
+```csharp
+public NestedClass3();
+```
+___
+
+*Documentation generated by [MdDocs](https://github.com/ap0llo/mddocs)*

docs/demoprojects/api/DemoProject/NestedTypesDemo/NestedClass2/NestedClass3/index.md

@@ -0,0 +1,25 @@
+# NestedTypesDemo.NestedClass2.NestedClass3 Class
+
+**Declaring Type:** [NestedTypesDemo.NestedClass2](../index.md)
+
+**Namespace:** [DemoProject](../../../index.md)
+
+**Assembly:** DemoProject
+
+This is an example of an nested class within a nested class
+
+```csharp
+public class NestedTypesDemo.NestedClass2.NestedClass3
+```
+
+**Inheritance:** object → NestedTypesDemo.NestedClass2.NestedClass3
+
+## Constructors
+
+| Name                                    | Description |
+| --------------------------------------- | ----------- |
+| [NestedClass3()](constructors/index.md) |             |
+
+___
+
+*Documentation generated by [MdDocs](https://github.com/ap0llo/mddocs)*

docs/demoprojects/api/DemoProject/NestedTypesDemo/NestedClass2/constructors/index.md

@@ -0,0 +1,10 @@
+# NestedTypesDemo.NestedClass2 Constructors
+
+**Declaring Type:** [NestedTypesDemo.NestedClass2](../index.md)
+
+```csharp
+public NestedClass2();
+```
+___
+
+*Documentation generated by [MdDocs](https://github.com/ap0llo/mddocs)*

docs/demoprojects/api/DemoProject/NestedTypesDemo/NestedClass2/index.md

@@ -0,0 +1,31 @@
+# NestedTypesDemo.NestedClass2 Class
+
+**Declaring Type:** [NestedTypesDemo](../index.md)
+
+**Namespace:** [DemoProject](../../index.md)
+
+**Assembly:** DemoProject
+
+This is an example of a nested class that in turn contains nested types
+
+```csharp
+public class NestedTypesDemo.NestedClass2
+```
+
+**Inheritance:** object → NestedTypesDemo.NestedClass2
+
+## Constructors
+
+| Name                                    | Description |
+| --------------------------------------- | ----------- |
+| [NestedClass2()](constructors/index.md) |             |
+
+## Nested Types
+
+| Name                                                               | Description                                                 |
+| ------------------------------------------------------------------ | ----------------------------------------------------------- |
+| [NestedTypesDemo.NestedClass2.NestedClass3](NestedClass3/index.md) | This is an example of an nested class within a nested class |
+
+___
+
+*Documentation generated by [MdDocs](https://github.com/ap0llo/mddocs)*

docs/demoprojects/api/DemoProject/NestedTypesDemo/NestedInterface1/index.md

@@ -0,0 +1,16 @@
+# NestedTypesDemo.NestedInterface1 Interface
+
+**Declaring Type:** [NestedTypesDemo](../index.md)
+
+**Namespace:** [DemoProject](../../index.md)
+
+**Assembly:** DemoProject
+
+This is an example of a nested interface
+
+```csharp
+public interface NestedTypesDemo.NestedInterface1
+```
+___
+
+*Documentation generated by [MdDocs](https://github.com/ap0llo/mddocs)*

docs/demoprojects/api/DemoProject/NestedTypesDemo/constructors/index.md

@@ -0,0 +1,10 @@
+# NestedTypesDemo Constructors
+
+**Declaring Type:** [NestedTypesDemo](../index.md)
+
+```csharp
+public NestedTypesDemo();
+```
+___
+
+*Documentation generated by [MdDocs](https://github.com/ap0llo/mddocs)*

docs/demoprojects/api/DemoProject/NestedTypesDemo/index.md

@@ -0,0 +1,31 @@
+# NestedTypesDemo Class
+
+**Namespace:** [DemoProject](../index.md)
+
+**Assembly:** DemoProject
+
+This class shows an example of how the documentation for nested types looks.
+
+```csharp
+public class NestedTypesDemo
+```
+
+**Inheritance:** object → NestedTypesDemo
+
+## Constructors
+
+| Name                                       | Description |
+| ------------------------------------------ | ----------- |
+| [NestedTypesDemo()](constructors/index.md) |             |
+
+## Nested Types
+
+| Name                                                          | Description                                                             |
+| ------------------------------------------------------------- | ----------------------------------------------------------------------- |
+| [NestedTypesDemo.NestedClass1](NestedClass1/index.md)         | This is an example of a nested class                                    |
+| [NestedTypesDemo.NestedClass2](NestedClass2/index.md)         | This is an example of a nested class that in turn contains nested types |
+| [NestedTypesDemo.NestedInterface1](NestedInterface1/index.md) | This is an example of a nested interface                                |
+
+___
+
+*Documentation generated by [MdDocs](https://github.com/ap0llo/mddocs)*

docs/demoprojects/api/DemoProject/index.md

@@ -2,14 +2,18 @@
 
 ## Classes
 
-| Name                                                                        | Description                                                                                     |
-| --------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------- |
-| [DemoAttribute](DemoAttribute/index.md)                                     | An example of an custom attribute class for methods                                             |
-| [DemoClass](DemoClass/index.md)                                             | A class meant to demonstrate how the generated documentation looks like.                        |
-| [DemoClass\<T1, T2\>](DemoClass-2/index.md)                                 | An example of an generic class.                                                                 |
-| [DemoPropertyAnnotationAttribute](DemoPropertyAnnotationAttribute/index.md) | An example of a custom attribute that is used to annotate a property with custom flags.         |
-| [ListExample](ListExample/index.md)                                         | Example class to showcase the different supported list formats.                                 |
-| [ObsoleteDemoClass](ObsoleteDemoClass/index.md)                             | A class meant to demonstrate how the generated documentation for a deprecated class looks like. |
+| Name                                                                                            | Description                                                                                     |
+| ----------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------- |
+| [DemoAttribute](DemoAttribute/index.md)                                                         | An example of an custom attribute class for methods                                             |
+| [DemoClass](DemoClass/index.md)                                                                 | A class meant to demonstrate how the generated documentation looks like.                        |
+| [DemoClass\<T1, T2\>](DemoClass-2/index.md)                                                     | An example of an generic class.                                                                 |
+| [DemoPropertyAnnotationAttribute](DemoPropertyAnnotationAttribute/index.md)                     | An example of a custom attribute that is used to annotate a property with custom flags.         |
+| [ListExample](ListExample/index.md)                                                             | Example class to showcase the different supported list formats.                                 |
+| [NestedTypesDemo](NestedTypesDemo/index.md)                                                     | This class shows an example of how the documentation for nested types looks.                    |
+| [NestedTypesDemo.NestedClass1](NestedTypesDemo/NestedClass1/index.md)                           | This is an example of a nested class                                                            |
+| [NestedTypesDemo.NestedClass2](NestedTypesDemo/NestedClass2/index.md)                           | This is an example of a nested class that in turn contains nested types                         |
+| [NestedTypesDemo.NestedClass2.NestedClass3](NestedTypesDemo/NestedClass2/NestedClass3/index.md) | This is an example of an nested class within a nested class                                     |
+| [ObsoleteDemoClass](ObsoleteDemoClass/index.md)                                                 | A class meant to demonstrate how the generated documentation for a deprecated class looks like. |
 
 ## Structs
 
@@ -19,9 +23,10 @@
 
 ## Interfaces
 
-| Name                                      | Description                                                                                 |
-| ----------------------------------------- | ------------------------------------------------------------------------------------------- |
-| [IDemoInterface](IDemoInterface/index.md) | A interface meant to demonstrate how the generated documentation for interfaces looks like. |
+| Name                                                                          | Description                                                                                 |
+| ----------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------- |
+| [IDemoInterface](IDemoInterface/index.md)                                     | A interface meant to demonstrate how the generated documentation for interfaces looks like. |
+| [NestedTypesDemo.NestedInterface1](NestedTypesDemo/NestedInterface1/index.md) | This is an example of a nested interface                                                    |
 
 ## Enums
 

src/MdDocs.ApiReference.DemoProject/NestedTypesDemo.cs

@@ -0,0 +1,32 @@
+namespace DemoProject
+{
+    /// <summary>
+    /// This class shows an example of how the documentation for nested types looks.
+    /// </summary>
+    public class NestedTypesDemo
+    {
+        /// <summary>
+        /// This is an example of a nested class
+        /// </summary>
+        public class NestedClass1
+        { }
+
+        /// <summary>
+        /// This is an example of a nested class that in turn contains nested types
+        /// </summary>
+        public class NestedClass2
+        {
+            /// <summary>
+            /// This is an example of an nested class within a nested class
+            /// </summary>
+            public class NestedClass3
+            { }
+        }
+
+        /// <summary>
+        /// This is an example of a nested interface
+        /// </summary>
+        public interface NestedInterface1
+        { }
+    }
+}