DOC: add references to Lomb-Scargle explainer
DOC: add references to Lomb-Scargle explainer

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