doc: point to the main share-safe doc in the "mismatch" config
User should be able to find their way with that.
Differential Revision: https://phab.mercurial-scm.org/D9840
#require black test-repo $ cd $RUNTESTDIR/.. $ black --config=black.toml --check --diff `hg files 'set:(**.py + grep("^#!.*python")) - mercurial/thirdparty/**'`