docs(ngController): remove obsolete mention of scope as this in controller

Controllers are now (since angular 1.0) instantiated as regular constructorsand the scope
is injectable as $scope rather than being referenced as `this` in controller methods.

Author: vin

src/ng/directive/ngController.js

@@ -25,11 +25,9 @@
  *
  * @example
  * Here is a simple form for editing user contact information. Adding, removing, clearing, and
- * greeting are methods declared on the controller (see source tab). These methods can
- * easily be called from the angular markup. Notice that the scope becomes the `this` for the
- * controller's instance. This allows for easy access to the view data from the controller. Also
- * notice that any changes to the data are automatically reflected in the View without the need
- * for a manual update.
+ * greeting are methods declared on the $scope by the controller (see source tab). These methods can
+ * easily be called from the angular markup. Notice that any changes to the data are automatically
+ * reflected in the View without the need for a manual update.
    <doc:example>
      <doc:source>
       <script>