Document the options parameter of $animate functions

[djdmbrwsk]

Unless I missed it, there is no documentation explaining the options parameter that is optional in a bunch of the $animate service's functions. Ex:

$animate.enter(element, parent, [after], [options]);

I just spent a bit digging through the source to finally find you can pass in an object like this:

{
  addClass: 'some-new-class',
  removeClass: ' some-old-class'
}

[Narretz]

@djdmbrwsk Would you like to submit a PR which adds the info to the docs?