DOC: stats: fix a header in `stats.sampling` tutorial
DOC: stats: fix a header in `stats.sampling` tutorial

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