DOC: fix parameter name doc for discrete distributions (#6631)
DOC: fix parameter name doc for discrete distributions (#6631)

Because the documentation templates are re-used between continuous and discrete variables, the documented name of the first parameter of many functions of discrete was x although the actual parameter expected by the function was k.

aeklant/scipy,endolith/scipy,anntzer/scipy,e-q/scipy,pizzathief/scipy,scipy/scipy,zerothi/scipy,nmayorov/scipy,ilayn/scipy,WarrenWeckesser/scipy,bkendzior/scipy,anntzer/scipy,vigna/scipy,nmayorov/scipy,ilayn/scipy,apbard/scipy,befelix/scipy,josephcslater/scipy,jjhelmus/scipy,aeklant/scipy,maniteja123/scipy,kalvdans/scipy,tylerjereddy/scipy,lhilt/scipy,WarrenWeckesser/scipy,Eric89GXL/scipy,scipy/scipy,mdhaber/scipy,apbard/scipy,nonhermitian/scipy,jakevdp/scipy,Eric89GXL/scipy,josephcslater/scipy,nonhermitian/scipy,jamestwebber/scipy,apbard/scipy,jor-/scipy,bkendzior/scipy,pschella/scipy,andyfaff/scipy,mikebenfield/scipy,WarrenWeckesser/scipy,andyfaff/scipy,e-q/scipy,scipy/scipy,perimosocordiae/scipy,WarrenWeckesser/scipy,kalvdans/scipy,ilayn/scipy,vigna/scipy,dominicelse/scipy,gfyoung/scipy,pbrod/scipy,matthewalbani/scipy,lhilt/scipy,grlee77/scipy,gfyoung/scipy,Eric89GXL/scipy,endolith/scipy,person142/scipy,zerothi/scipy,person142/scipy,rgommers/scipy,mdhaber/scipy,aeklant/scipy,pizzathief/scipy,kalvdans/scipy,pizzathief/scipy,perimosocordiae/scipy,josephcslater/scipy,pbrod/scipy,ilayn/scipy,nmayorov/scipy,gdooper/scipy,perimosocordiae/scipy,perimosocordiae/scipy,josephcslater/scipy,jakevdp/scipy,mdhaber/scipy,maniteja123/scipy,befelix/scipy,jamestwebber/scipy,gertingold/scipy,arokem/scipy,matthewalbani/scipy,pyramania/scipy,scipy/scipy,Eric89GXL/scipy,Stefan-Endres/scipy,tylerjereddy/scipy,pschella/scipy,maniteja123/scipy,pschella/scipy,vigna/scipy,gertingold/scipy,e-q/scipy,mdhaber/scipy,person142/scipy,ilayn/scipy,grlee77/scipy,WarrenWeckesser/scipy,pizzathief/scipy,scipy/scipy,mikebenfield/scipy,gdooper/scipy,jor-/scipy,gdooper/scipy,pschella/scipy,rgommers/scipy,gfyoung/scipy,Stefan-Endres/scipy,pyramania/scipy,jamestwebber/scipy,endolith/scipy,dominicelse/scipy,gertingold/scipy,apbard/scipy,endolith/scipy,matthew-brett/scipy,andyfaff/scipy,jjhelmus/scipy,pbrod/scipy,nmayorov/scipy,matthew-brett/scipy,tylerjereddy/scipy,maniteja123/scipy,matthewalbani/scipy,pbrod/scipy,bkendzior/scipy,aarchiba/scipy,jamestwebber/scipy,aarchiba/scipy,josephcslater/scipy,mikebenfield/scipy,gfyoung/scipy,aarchiba/scipy,anntzer/scipy,gdooper/scipy,dominicelse/scipy,gertingold/scipy,andyfaff/scipy,aeklant/scipy,aeklant/scipy,matthewalbani/scipy,arokem/scipy,bkendzior/scipy,Eric89GXL/scipy,jamestwebber/scipy,matthewalbani/scipy,pizzathief/scipy,kalvdans/scipy,vigna/scipy,gfyoung/scipy,gertingold/scipy,rgommers/scipy,grlee77/scipy,pyramania/scipy,jor-/scipy,e-q/scipy,gdooper/scipy,vigna/scipy,lhilt/scipy,aarchiba/scipy,jjhelmus/scipy,Stefan-Endres/scipy,Stefan-Endres/scipy,grlee77/scipy,perimosocordiae/scipy,Stefan-Endres/scipy,matthew-brett/scipy,anntzer/scipy,rgommers/scipy,mikebenfield/scipy,nmayorov/scipy,person142/scipy,Stefan-Endres/scipy,ilayn/scipy,tylerjereddy/scipy,jjhelmus/scipy,mdhaber/scipy,nonhermitian/scipy,maniteja123/scipy,anntzer/scipy,befelix/scipy,perimosocordiae/scipy,grlee77/scipy,pyramania/scipy,Eric89GXL/scipy,endolith/scipy,rgommers/scipy,arokem/scipy,nonhermitian/scipy,pyramania/scipy,jakevdp/scipy,apbard/scipy,zerothi/scipy,pbrod/scipy,tylerjereddy/scipy,pschella/scipy,zerothi/scipy,scipy/scipy,zerothi/scipy,anntzer/scipy,jor-/scipy,zerothi/scipy,jakevdp/scipy,jjhelmus/scipy,jakevdp/scipy,arokem/scipy,arokem/scipy,maniteja123/scipy,mikebenfield/scipy,aarchiba/scipy,kalvdans/scipy,andyfaff/scipy,jor-/scipy,dominicelse/scipy,matthew-brett/scipy,matthew-brett/scipy,andyfaff/scipy,befelix/scipy,mdhaber/scipy,e-q/scipy,nonhermitian/scipy,endolith/scipy,dominicelse/scipy,pbrod/scipy,lhilt/scipy,befelix/scipy,lhilt/scipy,WarrenWeckesser/scipy,person142/scipy,bkendzior/scipy