Fix reference links in API docs [docs only]
Fix reference links in API docs [docs only]

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