clarified some of the `render` method documentation
clarified some of the `render` method documentation

saimn/astropy,mhvk/astropy,astropy/astropy,larrybradley/astropy,lpsinger/astropy,joergdietrich/astropy,funbaker/astropy,aleksandr-bakanov/astropy,joergdietrich/astropy,mhvk/astropy,funbaker/astropy,AustereCuriosity/astropy,tbabej/astropy,stargaser/astropy,funbaker/astropy,tbabej/astropy,DougBurke/astropy,tbabej/astropy,AustereCuriosity/astropy,mhvk/astropy,larrybradley/astropy,saimn/astropy,joergdietrich/astropy,pllim/astropy,MSeifert04/astropy,bsipocz/astropy,bsipocz/astropy,StuartLittlefair/astropy,StuartLittlefair/astropy,dhomeier/astropy,lpsinger/astropy,StuartLittlefair/astropy,kelle/astropy,stargaser/astropy,pllim/astropy,aleksandr-bakanov/astropy,mhvk/astropy,aleksandr-bakanov/astropy,stargaser/astropy,kelle/astropy,dhomeier/astropy,StuartLittlefair/astropy,lpsinger/astropy,mhvk/astropy,stargaser/astropy,funbaker/astropy,joergdietrich/astropy,joergdietrich/astropy,bsipocz/astropy,saimn/astropy,MSeifert04/astropy,aleksandr-bakanov/astropy,kelle/astropy,MSeifert04/astropy,saimn/astropy,pllim/astropy,AustereCuriosity/astropy,kelle/astropy,tbabej/astropy,DougBurke/astropy,tbabej/astropy,kelle/astropy,pllim/astropy,AustereCuriosity/astropy,larrybradley/astropy,dhomeier/astropy,astropy/astropy,larrybradley/astropy,astropy/astropy,AustereCuriosity/astropy,astropy/astropy,pllim/astropy,StuartLittlefair/astropy,MSeifert04/astropy,DougBurke/astropy,larrybradley/astropy,dhomeier/astropy,dhomeier/astropy,astropy/astropy,DougBurke/astropy,lpsinger/astropy,bsipocz/astropy,saimn/astropy,lpsinger/astropy