Revised and added headings.

activemodel/lib/active_model/naming.rb

@@ -34,7 +34,7 @@ module ActiveModel
       I18n.translate(defaults.shift, options)
     end
   end
-  
+
   # == Active Model Naming
   #
   # Creates a +model_name+ method on your object.

activemodel/lib/active_model/observing.rb

@@ -9,6 +9,8 @@ module ActiveModel
     extend ActiveSupport::Concern
 
     module ClassMethods
+      # == Active Model Observers Activation
+      # 
       # Activates the observers assigned. Examples:
       #
       #   # Calls PersonObserver.instance
@@ -89,6 +91,8 @@ module ActiveModel
       end
   end
 
+  # == Active Model Observers
+  #
   # Observer classes respond to lifecycle callbacks to implement trigger-like
   # behavior outside the original class. This is a great way to reduce the
   # clutter that normally comes when the model class is burdened with

activemodel/lib/active_model/serialization.rb

@@ -2,6 +2,8 @@ require 'active_support/core_ext/hash/except'
 require 'active_support/core_ext/hash/slice'
 
 module ActiveModel
+  # == Active Model Serialization
+  # 
   # Provides a basic serialization to a serializable_hash for your object.
   # 
   # A minimal implementation could be: