Display a message when entering insert mode while readonly
Display a message when entering insert mode while readonly

Fixes #1050

jjthrash/kakoune,Somasis/kakoune,mawww/kakoune,ekie/kakoune,occivink/kakoune,alexherbo2/kakoune,lenormf/kakoune,lenormf/kakoune,occivink/kakoune,ekie/kakoune,lenormf/kakoune,casimir/kakoune,alexherbo2/kakoune,ekie/kakoune,danr/kakoune,jjthrash/kakoune,alexherbo2/kakoune,jjthrash/kakoune,danr/kakoune,jkonecny12/kakoune,occivink/kakoune,danr/kakoune,mawww/kakoune,jjthrash/kakoune,jkonecny12/kakoune,lenormf/kakoune,Somasis/kakoune,Somasis/kakoune,mawww/kakoune,Somasis/kakoune,casimir/kakoune,alexherbo2/kakoune,ekie/kakoune,jkonecny12/kakoune,occivink/kakoune,mawww/kakoune,casimir/kakoune,jkonecny12/kakoune,casimir/kakoune,danr/kakoune