Clarify docstring
Clarify docstring

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