smallrye#1670: update documentation

docs/directives.md

@@ -1,5 +1,20 @@
 # Directives
 
+## Custom Directives
+
+You can add your own [GraphQL Directives](https://spec.graphql.org/draft/#sec-Language.Directives) by writing
+a corresponding Java Annotation and annotate it as `@Directive`, e.g.:
+
+```java
+@Directive(on = { OBJECT, INTERFACE })
+@Description("Just a test")
+@Retention(RUNTIME)
+public @interface MyDirective {
+}
+```
+
+Directives can be repeatable, see the `@Key` annotation for an example.
+
 ## Directives generated from Bean Validation annotations
 
 If your project uses Bean Validation to validate fields on input types and operation arguments, and you enable 
@@ -23,4 +38,4 @@ BV annotations are listed here):
 
 Note: The `@NotNull` annotation does not map to a directive, instead it makes the GraphQL type non-nullable.
 
-Constraints will only appear on fields of input types and operation arguments.
+Constraints will only appear on fields of input types and operation arguments.

docs/federation.md

@@ -1,6 +1,6 @@
 # Federation
 
-To enable support for [GraphQL Federation](https://www.apollographql.com/docs/federation), simply set the `smallrye.graphql.federation.enabled` config key to `true`.
+Support for [GraphQL Federation](https://www.apollographql.com/docs/federation) is enabled by default. If you add one of the federation annotations, the corresponding directives will be declared to your schema and the additional Federation queries will be added automatically. You can also disable Federation completely by setting the `smallrye.graphql.federation.enabled` config key to `false`.
 
 You can add the Federation directives by using the equivalent Java annotation, e.g. to extend a `Product` entity with a `price` field, you can write a class:
 
@@ -37,15 +37,15 @@ import org.eclipse.microprofile.graphql.Query;
 public class Prices {
     @Query
     public Product product(@Id String id) {
-        return ...;
+        return ...
     }
 }
 ```
 
 The GraphQL Schema then contains:
 
 ```graphql
-type Product @extends @key(fields : ["id"]) {
+type Product @extends @key(fields : "id") {
     id: ID
     price: Int
 }
@@ -58,3 +58,5 @@ type Query {
     product(id: ID): Product
 }
 ```
+
+If you can resolve, e.g., the product with different types of ids, you can add multiple `@Key` annotations.