docs(ngAnimate.$animate): fix classes during the various animation phases

I am not 100% sure for the class additions (although I am 99+% sure).
(If someone could double-check (@matsko ideally ?), that would be great :smiley:)
Fixing double-quotes wasn't the primary goal fr this PR, but since I got to it, I should have used that _Find-and-Replace_ functionality :D