Clarify documentation regarding moment injection

[kibertoad]

Current documentation makes it extremely unclear that while you do inject "angularMoment" into your module, you do not inject it where you intend to use it (e. g. service or controller), you inject "moment" instead.

The only place where I found that mentioned was #236 , while it should definitely be mentioned loud and clear in the main documentation in example part. :)

[jwanglof]

Created a PR for this =)
Thanks for the link to the other issue