docs(sanitize): add @description section

Author: Alan Klement

src/ngSanitize/sanitize.js

@@ -4,6 +4,25 @@
  * @ngdoc overview
  * @name ngSanitize
  * @description
+ * 
+ * The `ngSanitize` module provides functionality to sanitize HTML.
+ * 
+ * # Installation
+ * As a separate module, it must be loaded after Angular core is loaded; otherwise, an 'Uncaught Error:
+ * No module: ngSanitize' runtime error will occur.
+ *
+ * <pre>
+ *   <script src="angular.js"></script>
+ *   <script src="angular-sanitize.js"></script>
+ * </pre>
+ *
+ * # Usage
+ * To make sure the module is available to your application, declare it as a dependency of you application
+ * module.
+ *
+ * <pre>
+ *   angular.module('app', ['ngSanitize']);
+ * </pre>
  */
 
 /*