Clarify .shape documentation
Clarify .shape documentation

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