Update controller.ngdoc

If it is not recommended to use a constructor function to create controllers, why should it be shown as possible in the documentation? 

One of the most common complaints about AngularJS is that it doesn't enforce any variety of convention, this is intentional and I generally like this however if we can avoid outright bad implementations or examples I believe we should.

The only real reason to avoid doing so is to avoid introducing the potential new user to a somewhat complex new concept, however it is better to introduce new users to best practices instead of overly simplified examples.