replace deprecated randomly_sample_sphere in docs
replace deprecated randomly_sample_sphere in docs

pllim/astropy,StuartLittlefair/astropy,astropy/astropy,saimn/astropy,larrybradley/astropy,astropy/astropy,pllim/astropy,StuartLittlefair/astropy,aleksandr-bakanov/astropy,lpsinger/astropy,larrybradley/astropy,mhvk/astropy,saimn/astropy,larrybradley/astropy,mhvk/astropy,larrybradley/astropy,aleksandr-bakanov/astropy,aleksandr-bakanov/astropy,astropy/astropy,lpsinger/astropy,astropy/astropy,saimn/astropy,saimn/astropy,lpsinger/astropy,aleksandr-bakanov/astropy,mhvk/astropy,pllim/astropy,lpsinger/astropy,larrybradley/astropy,StuartLittlefair/astropy,astropy/astropy,mhvk/astropy,saimn/astropy,StuartLittlefair/astropy,lpsinger/astropy,pllim/astropy,mhvk/astropy,StuartLittlefair/astropy,pllim/astropy