Document mercurial configuration for contributing * how to use master/review repositories * how to send the "Available at" command in patchbomb emails * how to add the "cubicweb" flag in patchbomb emails * how to use our "jenkins" mercurial extension Closes #17243538

missing-dep-for-interpreter make => make | build-essential | dpkg-dev (usr/*/cubicweb/skeleton/debian/rules)
embedded-javascript-library usr/share/cubicweb/cubes/shared/data/jquery.js