docs($exceptionHandler): add a note about cases when exceptions are not delegated...

...to the $exceptionHandler

Add a note in $exceptionHandler's documentation about cases when exceptions are not delegated to the
$exceptionHandler, because they are executed outside of the Angular context. Most notable such
cases being the DOM event listeners registered using jqLite's/jQuery's on/bind methods.

Closes #7909
@caitp : I pushed a second commit with a shortened message.

I don't feel strongly about this anyway. I submitted a PR because it was [asked for][1], so feel free to just drop it.

[1]: https://github.com/angular/angular.js/issues/7909#issuecomment-57024864