add versionchanged tag for Animation step
add versionchanged tag for Animation step

ref https://github.com/kivy/kivy/pull/4563
akshayaurora/kivy,aron-bordin/kivy,KeyWeeUsr/kivy,Cheaterman/kivy,rafalo1333/kivy,tony/kivy,janssen/kivy,bionoid/kivy,manthansharma/kivy,jkankiewicz/kivy,rafalo1333/kivy,tony/kivy,KeyWeeUsr/kivy,LogicalDash/kivy,jkankiewicz/kivy,inclement/kivy,matham/kivy,aron-bordin/kivy,akshayaurora/kivy,jegger/kivy,autosportlabs/kivy,janssen/kivy,Cheaterman/kivy,Cheaterman/kivy,kivy/kivy,darkopevec/kivy,janssen/kivy,kived/kivy,jkankiewicz/kivy,aron-bordin/kivy,tony/kivy,janssen/kivy,darkopevec/kivy,kivy/kivy,kived/kivy,kivy/kivy,rnixx/kivy,bionoid/kivy,matham/kivy,darkopevec/kivy,inclement/kivy,inclement/kivy,jegger/kivy,autosportlabs/kivy,rafalo1333/kivy,LogicalDash/kivy,KeyWeeUsr/kivy,kived/kivy,bionoid/kivy,LogicalDash/kivy,Cheaterman/kivy,darkopevec/kivy,KeyWeeUsr/kivy,jkankiewicz/kivy,akshayaurora/kivy,manthansharma/kivy,aron-bordin/kivy,matham/kivy,jegger/kivy,jegger/kivy,matham/kivy,manthansharma/kivy,autosportlabs/kivy,rnixx/kivy,rnixx/kivy,LogicalDash/kivy,bionoid/kivy,manthansharma/kivy