Add note about PyYAML dependency for ECSV
Add note about PyYAML dependency for ECSV

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