update release instructions
update release instructions

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