Change link ref to 'astropy mailing list' to fix sphinx warning
Change link ref to 'astropy mailing list' to fix sphinx warning

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