add missing "versionadded" statement for scale parameter
add missing "versionadded" statement for scale parameter

akshayaurora/kivy,inclement/kivy,inclement/kivy,kivy/kivy,matham/kivy,kivy/kivy,matham/kivy,kivy/kivy,akshayaurora/kivy,matham/kivy,inclement/kivy,rnixx/kivy,rnixx/kivy,matham/kivy,akshayaurora/kivy,rnixx/kivy