add documentation to Sequence's cancel_property
add documentation to Sequence's cancel_property

matham/kivy,bionoid/kivy,Cheaterman/kivy,janssen/kivy,LogicalDash/kivy,kived/kivy,akshayaurora/kivy,kivy/kivy,rafalo1333/kivy,jkankiewicz/kivy,tony/kivy,rnixx/kivy,manthansharma/kivy,kivy/kivy,darkopevec/kivy,aron-bordin/kivy,tony/kivy,bionoid/kivy,manthansharma/kivy,jegger/kivy,kivy/kivy,manthansharma/kivy,LogicalDash/kivy,darkopevec/kivy,Cheaterman/kivy,kived/kivy,LogicalDash/kivy,aron-bordin/kivy,Cheaterman/kivy,jkankiewicz/kivy,darkopevec/kivy,bionoid/kivy,KeyWeeUsr/kivy,jegger/kivy,aron-bordin/kivy,inclement/kivy,inclement/kivy,jegger/kivy,akshayaurora/kivy,rnixx/kivy,KeyWeeUsr/kivy,Cheaterman/kivy,janssen/kivy,inclement/kivy,matham/kivy,tony/kivy,jegger/kivy,matham/kivy,autosportlabs/kivy,autosportlabs/kivy,kived/kivy,rafalo1333/kivy,rafalo1333/kivy,jkankiewicz/kivy,rnixx/kivy,LogicalDash/kivy,aron-bordin/kivy,KeyWeeUsr/kivy,matham/kivy,akshayaurora/kivy,bionoid/kivy,jkankiewicz/kivy,manthansharma/kivy,darkopevec/kivy,autosportlabs/kivy,KeyWeeUsr/kivy,janssen/kivy,janssen/kivy