doc.kak: fix handling of lines begining with * or -
doc.kak: fix handling of lines begining with * or -

Those were considered as any other lines for paragraph joining,
threat them as a new paragraph start, to correctly handle asciidoc
lists.

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