docs(tutorial/2): add e2e test missing filename

Add `__`test/e2e/scenarios.js`:__` to denote which file we should change
to add the behavioral tests.

Closes #13673

Author: monkpit

docs/content/tutorial/step_02.ngdoc

@@ -132,6 +132,8 @@ The "Angular way" of separating controller from the view, makes it easy to test
 developed. If our controller is available on the global namespace then we could simply instantiate it
 with a mock `scope` object:
 
+__`test/e2e/scenarios.js`:__
+
 ```js
 describe('PhoneListCtrl', function(){