Makefile: use git-describe to get the version string
Makefile: use git-describe to get the version string

That means we can just tag releases and the version will be taken
from the tag to generate the tarball.

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