cleanup: update references to /help/ that should now be /helptext/
I noticed this only because the WiX build was broken after
2e017696181f. I haven't tested this change with WiX, but it seems
pretty obvious by inspection this should fix it.
Differential Revision: https://phab.mercurial-scm.org/D7472
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}