diff --git a/docs/middleware.md b/docs/middleware.md
index ca5e2f1f4ed..b74452affbd 100644
--- a/docs/middleware.md
+++ b/docs/middleware.md
@@ -175,7 +175,7 @@ schema.pre('save', function(next) {
});
```
-
+### Use Cases
Middleware are useful for atomizing model logic. Here are some other ideas:
@@ -184,7 +184,7 @@ Middleware are useful for atomizing model logic. Here are some other ideas:
* asynchronous defaults
* asynchronous tasks that a certain action triggers
-
+### Errors in Pre Hooks {#error-handling}
If any pre hook errors out, mongoose will not execute subsequent middleware
or the hooked function. Mongoose will instead pass an error to the callback
diff --git a/docs/subdocs.md b/docs/subdocs.md
index eeb4c2973b0..5bd37433435 100644
--- a/docs/subdocs.md
+++ b/docs/subdocs.md
@@ -313,7 +313,7 @@ doc.level1.level2.parent() === doc.level1; // true
doc.level1.level2.ownerDocument() === doc; // true
```
-
+### Alternate declaration syntax for arrays {#altsyntaxarrays}
If you create a schema with an array of objects, Mongoose will automatically convert the object to a schema for you:
diff --git a/docs/tutorials/lean.md b/docs/tutorials/lean.md
index 404d352de4f..e11641449d1 100644
--- a/docs/tutorials/lean.md
+++ b/docs/tutorials/lean.md
@@ -12,7 +12,7 @@ In this tutorial, you'll learn more about the tradeoffs of using `lean()`.
* [Plugins](#plugins)
* [BigInts](#bigints)
-
+## Using Lean
By default, Mongoose queries return an instance of the
[Mongoose `Document` class](../api/document.html#Document). Documents are much
@@ -53,7 +53,7 @@ and virtuals don't run if you enable `lean`.
[require:Lean Tutorial.*getters and virtuals]
```
-
+## Lean and Populate
[Populate](../populate.html) works with `lean()`. If you
use both `populate()` and `lean()`, the `lean` option propagates to the
@@ -70,7 +70,7 @@ populated documents as well. In the below example, both the top-level
[require:Lean Tutorial.*virtual populate]
```
-
+## When to Use Lean
If you're executing a query and sending the results without modification to,
say, an [Express response](http://expressjs.com/en/4x/api.html#res), you should