add a note about widget and property name requirements
add a note about widget and property name requirements

bionoid/kivy,andnovar/kivy,kived/kivy,CuriousLearner/kivy,el-ethan/kivy,andnovar/kivy,kivy/kivy,el-ethan/kivy,inclement/kivy,cbenhagen/kivy,arlowhite/kivy,matham/kivy,tony/kivy,CuriousLearner/kivy,rnixx/kivy,tony/kivy,manthansharma/kivy,matham/kivy,LogicalDash/kivy,bionoid/kivy,janssen/kivy,andnovar/kivy,janssen/kivy,darkopevec/kivy,jegger/kivy,LogicalDash/kivy,rafalo1333/kivy,darkopevec/kivy,kived/kivy,bionoid/kivy,tony/kivy,KeyWeeUsr/kivy,matham/kivy,rnixx/kivy,akshayaurora/kivy,jkankiewicz/kivy,akshayaurora/kivy,aron-bordin/kivy,janssen/kivy,rafalo1333/kivy,KeyWeeUsr/kivy,jegger/kivy,matham/kivy,CuriousLearner/kivy,rnixx/kivy,autosportlabs/kivy,kived/kivy,el-ethan/kivy,kivy/kivy,aron-bordin/kivy,janssen/kivy,jegger/kivy,jkankiewicz/kivy,cbenhagen/kivy,Cheaterman/kivy,Cheaterman/kivy,darkopevec/kivy,akshayaurora/kivy,aron-bordin/kivy,cbenhagen/kivy,inclement/kivy,inclement/kivy,rafalo1333/kivy,jegger/kivy,kivy/kivy,autosportlabs/kivy,Cheaterman/kivy,vitorio/kivy,jkankiewicz/kivy,manthansharma/kivy,bionoid/kivy,darkopevec/kivy,KeyWeeUsr/kivy,autosportlabs/kivy,aron-bordin/kivy,vitorio/kivy,KeyWeeUsr/kivy,Cheaterman/kivy,LogicalDash/kivy,arlowhite/kivy,LogicalDash/kivy,vitorio/kivy,manthansharma/kivy,arlowhite/kivy,manthansharma/kivy,jkankiewicz/kivy