docs(guides/directive): add (') to contraction


add apostrophe (') to contraction
docs(ngAnimate): change "&#64" to "@" symbol

Previously, we had problems with code that contained symbols that looked
like jsdoc directives.  This has now been fixed so we can convert these
HTML character codes back to @ signs.

Closes #6822
Closes #6826
docs(guide): add ui-router to complementary libraries