MAINT: stats.rankdata: update nan_policy docstring
MAINT: stats.rankdata: update nan_policy docstring

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