fix typo in SkyCoord return docstring
fix typo in SkyCoord return docstring

[docs only]

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