cleanup markdown in docs

README.markdown

@@ -72,7 +72,7 @@ serializer and available as `@options` inside.
 
 To specify a custom serializer for an object, there are 2 options:
 
-1. Specify the serializer in your model:
+#### 1. Specify the serializer in your model:
 
 ```ruby
 class Post < ActiveRecord::Base
@@ -82,7 +82,7 @@ To specify a custom serializer for an object, there are 2 options:
 end
 ```
 
-2. Specify the serializer when you render the object:
+#### 2. Specify the serializer when you render the object:
 
 ```ruby
 render :json => @post, :serializer => FancyPostSerializer
@@ -129,19 +129,19 @@ generates a root element "posts". To change it:
 You may disable the root element for arrays at the top level, which will result in
 more concise json. To disable the root element for arrays, you have 3 options:
 
-1. Disable root globally for in ArraySerializer. In an initializer:
+#### 1. Disable root globally for in ArraySerializer. In an initializer:
 
 ```ruby
 ActiveModel::ArraySerializer.root = false
 ```
 
-2. Disable root per render call in your controller:
+#### 2. Disable root per render call in your controller:
 
 ```ruby
 render :json => @posts, :root => false
 ```
 
-3. Create a custom ArraySerializer and render arrays with it:
+#### 3. Create a custom ArraySerializer and render arrays with it:
 
 ```ruby
 class CustomArraySerializer < ActiveModel::ArraySerializer