Add photometric API doc link [docs only]
Add photometric API doc link [docs only]

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