docs(tutorial/step-12): correct application name

Fixed wrong app name:
- phonecat -> phonecatApp, which meets the code in app.js

Closes angular#6611

Author: cchungmin

docs/content/tutorial/step_12.ngdoc

@@ -83,7 +83,7 @@ __`app/js/app.js`.__
 
 ```js
 // ...
-angular.module('phonecat', [
+angular.module('phonecatApp', [
   'ngRoute',
 
   'phonecatAnimations',