Relocate plugin section of test docs. Add more links [docs only]
Relocate plugin section of test docs. Add more links [docs only]

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