Adjust coordinate docs for the change in error message.
Adjust coordinate docs for the change in error message.

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