doc: use angle brackets for page{up,down} like for other key names
doc: use angle brackets for page{up,down} like for other key names

mawww/kakoune,Somasis/kakoune,casimir/kakoune,mawww/kakoune,danr/kakoune,lenormf/kakoune,alexherbo2/kakoune,jkonecny12/kakoune,Somasis/kakoune,jkonecny12/kakoune,jkonecny12/kakoune,Somasis/kakoune,lenormf/kakoune,danr/kakoune,casimir/kakoune,lenormf/kakoune,danr/kakoune,Somasis/kakoune,casimir/kakoune,jkonecny12/kakoune,mawww/kakoune,casimir/kakoune,mawww/kakoune,alexherbo2/kakoune,alexherbo2/kakoune,danr/kakoune,alexherbo2/kakoune,lenormf/kakoune