fix ylabel in sgr example [ci skip]
fix ylabel in sgr example [ci skip]

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