docs($anchorScroll) change MainCtrl to ScrollCtrl and add styling

Fix an issue where the example was not working due to referencing
the wrong controller in the html ng-controller attribute.

The demo was also unsightly due to it being too long to look reasonable
on the screen. Add overflow and height CSS styling to the containing
element to clean it up.
Merge branch 'anchorScroll_doc_fix' of https://github.com/blesh/angular.js into anchorScroll_doc_fix