Remove mention of astrpy 0.4 on top documentation page
Remove mention of astrpy 0.4 on top documentation page

Astropy-helpers has been split out for a long time. We are working towards 2.0 now, so I don't think we need to explain to people how live was before 0.4.

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