Clarify docs
Clarify docs

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