Update docstrings for add_column(s)
Update docstrings for add_column(s)

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