DOC: missing-bits: document rule on return object type
DOC: missing-bits: document rule on return object type

Stefan-Endres/scipy,anntzer/scipy,Stefan-Endres/scipy,scipy/scipy,WarrenWeckesser/scipy,anntzer/scipy,Stefan-Endres/scipy,andyfaff/scipy,anntzer/scipy,andyfaff/scipy,WarrenWeckesser/scipy,WarrenWeckesser/scipy,Stefan-Endres/scipy,WarrenWeckesser/scipy,scipy/scipy,WarrenWeckesser/scipy,scipy/scipy,Stefan-Endres/scipy,Stefan-Endres/scipy,scipy/scipy,andyfaff/scipy,scipy/scipy,WarrenWeckesser/scipy,anntzer/scipy,anntzer/scipy,scipy/scipy,andyfaff/scipy,andyfaff/scipy,anntzer/scipy,andyfaff/scipy