Update resource.md

Added an additional example to make the 'proxy' behavior of the resource more obvious

Author: shairez

guide/angular-data/resource/resource.md

@@ -27,6 +27,9 @@ var User = DS.defineResource('user');
 // The following are equivalent
 DS.find('user', 5);
 User.find(5);
+
+DS.destroy('user', 5);
+User.destroy(5);
 ```
 
 See [defineResource(definition)](/documentation/api/api/DS.sync_methods:defineResource) for detailed API information.