Update chain of responsibilities

Author: mgechev

README.md

@@ -560,7 +560,7 @@ Few sample AngularJS expressions are:
 (foo) ? bar : baz | toUpperCase
 ```
 
-### Observer (publish/subscribe)
+### Observer
 
 >The observer pattern is a software design pattern in which an object, called the subject, maintains a list of its dependents, called observers, and notifies them automatically of any state changes, usually by calling one of their methods. It is mainly used to implement distributed event handling systems.
 
@@ -629,6 +629,8 @@ myModule.controller('ChildCtrl', function ($scope) {
 });
 ```
 
+The different handlers from the UML diagram above are the different scopes, injected to the controllers.
+
 ### Active Record
 
 >The Active Record object is an object, which carries both data and behavior. Usually most of the data in these objects is persistent, responsibility of the Active Record object is to take care of the communication with the database in order to create, update, retrieve or delete the data. It may delegate this responsibility to lower level objects but calls to instance or static methods of the active record object cause the database communication.