rc/markdown: add another markdown extension (.mkd)
rc/markdown: add another markdown extension (.mkd)

occivink/kakoune,ekie/kakoune,flavius/kakoune,zakgreant/kakoune,mawww/kakoune,mawww/kakoune,flavius/kakoune,alexherbo2/kakoune,mawww/kakoune,lenormf/kakoune,casimir/kakoune,jjthrash/kakoune,casimir/kakoune,danr/kakoune,alexherbo2/kakoune,lenormf/kakoune,zakgreant/kakoune,jjthrash/kakoune,Asenar/kakoune,jjthrash/kakoune,casimir/kakoune,jkonecny12/kakoune,flavius/kakoune,alpha123/kakoune,elegios/kakoune,elegios/kakoune,Somasis/kakoune,Somasis/kakoune,occivink/kakoune,alpha123/kakoune,lenormf/kakoune,jkonecny12/kakoune,alexherbo2/kakoune,jjthrash/kakoune,danr/kakoune,casimir/kakoune,alpha123/kakoune,occivink/kakoune,Somasis/kakoune,flavius/kakoune,ekie/kakoune,zakgreant/kakoune,danr/kakoune,Asenar/kakoune,elegios/kakoune,occivink/kakoune,alpha123/kakoune,Asenar/kakoune,alexherbo2/kakoune,mawww/kakoune,ekie/kakoune,danr/kakoune,Asenar/kakoune,lenormf/kakoune,jkonecny12/kakoune,elegios/kakoune,zakgreant/kakoune,Somasis/kakoune,jkonecny12/kakoune,ekie/kakoune