minor typo in coordinates docs
minor typo in coordinates docs

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