Doc notes: Include the format-patch --notes option

git format-patch gained a --notes option. Tell the notes user.

Signed-off-by: Philip Oakley <philipoakley@iee.org>
Signed-off-by: Jeff King <peff@peff.net>

Documentation/git-notes.txt

@@ -39,6 +39,10 @@ message stored in the commit object, the notes are indented like the
 message, after an unindented line saying "Notes (<refname>):" (or
 "Notes:" for `refs/notes/commits`).
 
+Notes can also be added to patches prepared with `git format-patch` by
+using the `--notes` option. Such notes are added as a patch commentary
+after a three dash separator line.
+
 To change which notes are shown by 'git log', see the
 "notes.displayRef" configuration in linkgit:git-log[1].