rewriteutil: add pointer to help text when rewrite would cause divergence
The evolve extension's version of the hint has this pointer. I missed
it when I moved it to core.
Differential Revision: https://phab.mercurial-scm.org/D10723
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}