DOC: factorialk docstring inconsistent with code (#15590)
DOC: factorialk docstring inconsistent with code (#15590)

Co-authored-by: Pamphile Roy <5382f7c16494af1b573fda9cacaa4290463e84b1@gmail.com>
vigna/scipy,scipy/scipy,andyfaff/scipy,scipy/scipy,rgommers/scipy,endolith/scipy,rgommers/scipy,endolith/scipy,perimosocordiae/scipy,anntzer/scipy,WarrenWeckesser/scipy,rgommers/scipy,scipy/scipy,mdhaber/scipy,anntzer/scipy,mdhaber/scipy,perimosocordiae/scipy,ilayn/scipy,WarrenWeckesser/scipy,perimosocordiae/scipy,Stefan-Endres/scipy,WarrenWeckesser/scipy,anntzer/scipy,vigna/scipy,perimosocordiae/scipy,ilayn/scipy,WarrenWeckesser/scipy,Stefan-Endres/scipy,mdhaber/scipy,endolith/scipy,Stefan-Endres/scipy,mdhaber/scipy,mdhaber/scipy,endolith/scipy,endolith/scipy,Stefan-Endres/scipy,mdhaber/scipy,WarrenWeckesser/scipy,perimosocordiae/scipy,scipy/scipy,andyfaff/scipy,vigna/scipy,vigna/scipy,WarrenWeckesser/scipy,andyfaff/scipy,rgommers/scipy,andyfaff/scipy,ilayn/scipy,ilayn/scipy,anntzer/scipy,perimosocordiae/scipy,scipy/scipy,anntzer/scipy,scipy/scipy,endolith/scipy,ilayn/scipy,ilayn/scipy,anntzer/scipy,Stefan-Endres/scipy,vigna/scipy,andyfaff/scipy,Stefan-Endres/scipy,andyfaff/scipy,rgommers/scipy