added initial cosmology docs
added initial cosmology docs

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