small docstring fix
small docstring fix

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