docs(api/index): fix ambiguous ngClick link

ngClick appears in more than one module so we must make it explicit.
docs(ngHide): add icons back into the example
test(docs-app-e2e): refactor test inline with new docs app

The links to code elements have now changed: api/ng.directive:ngClick ->
api/ng/directive/ngClick.

Examples now run inside iframes, so we need to instruct Protractor to
switch to the example iframe.