DOC: add better example for `MultinomialQMC`.
DOC: add better example for `MultinomialQMC`.

[skip actions]

anntzer/scipy,Stefan-Endres/scipy,perimosocordiae/scipy,anntzer/scipy,WarrenWeckesser/scipy,endolith/scipy,mdhaber/scipy,WarrenWeckesser/scipy,andyfaff/scipy,rgommers/scipy,ilayn/scipy,perimosocordiae/scipy,ilayn/scipy,andyfaff/scipy,andyfaff/scipy,anntzer/scipy,scipy/scipy,scipy/scipy,WarrenWeckesser/scipy,anntzer/scipy,scipy/scipy,perimosocordiae/scipy,mdhaber/scipy,mdhaber/scipy,rgommers/scipy,ilayn/scipy,endolith/scipy,mdhaber/scipy,andyfaff/scipy,perimosocordiae/scipy,scipy/scipy,scipy/scipy,ilayn/scipy,andyfaff/scipy,perimosocordiae/scipy,anntzer/scipy,Stefan-Endres/scipy,Stefan-Endres/scipy,endolith/scipy,scipy/scipy,mdhaber/scipy,WarrenWeckesser/scipy,ilayn/scipy,perimosocordiae/scipy,Stefan-Endres/scipy,rgommers/scipy,rgommers/scipy,anntzer/scipy,endolith/scipy,WarrenWeckesser/scipy,WarrenWeckesser/scipy,Stefan-Endres/scipy,mdhaber/scipy,endolith/scipy,rgommers/scipy,endolith/scipy,andyfaff/scipy,Stefan-Endres/scipy,ilayn/scipy