DOC: update return type description for average
DOC: update return type description for average

rgommers/numpy,simongibbons/numpy,mhvk/numpy,jorisvandenbossche/numpy,abalkin/numpy,pizzathief/numpy,seberg/numpy,simongibbons/numpy,pizzathief/numpy,grlee77/numpy,shoyer/numpy,MSeifert04/numpy,abalkin/numpy,simongibbons/numpy,grlee77/numpy,mattip/numpy,shoyer/numpy,mhvk/numpy,gfyoung/numpy,ahaldane/numpy,rgommers/numpy,madphysicist/numpy,jorisvandenbossche/numpy,MSeifert04/numpy,numpy/numpy,gfyoung/numpy,anntzer/numpy,shoyer/numpy,jakirkham/numpy,mhvk/numpy,rgommers/numpy,MSeifert04/numpy,pizzathief/numpy,pbrod/numpy,numpy/numpy,madphysicist/numpy,shoyer/numpy,pbrod/numpy,seberg/numpy,WarrenWeckesser/numpy,ahaldane/numpy,jakirkham/numpy,mhvk/numpy,simongibbons/numpy,grlee77/numpy,MSeifert04/numpy,pdebuyl/numpy,pbrod/numpy,shoyer/numpy,rgommers/numpy,grlee77/numpy,pdebuyl/numpy,ahaldane/numpy,jakirkham/numpy,pdebuyl/numpy,mattip/numpy,madphysicist/numpy,jakirkham/numpy,numpy/numpy,mattip/numpy,ahaldane/numpy,WarrenWeckesser/numpy,abalkin/numpy,pizzathief/numpy,pizzathief/numpy,MSeifert04/numpy,endolith/numpy,charris/numpy,anntzer/numpy,charris/numpy,mattip/numpy,jorisvandenbossche/numpy,jorisvandenbossche/numpy,endolith/numpy,gfyoung/numpy,charris/numpy,mhvk/numpy,pdebuyl/numpy,charris/numpy,anntzer/numpy,jakirkham/numpy,simongibbons/numpy,WarrenWeckesser/numpy,jorisvandenbossche/numpy,pbrod/numpy,pbrod/numpy,WarrenWeckesser/numpy,madphysicist/numpy,numpy/numpy,madphysicist/numpy,seberg/numpy,grlee77/numpy,endolith/numpy,endolith/numpy,WarrenWeckesser/numpy,seberg/numpy,ahaldane/numpy,anntzer/numpy