SubmittingPatches: hints to know the status of a submitted patch.

"What happened to my patch" is pretty much a FAQ on the Git mailing list,
it deserves a few paragraphs in SubmittingPatches...
Signed-off-by: NMatthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/SubmittingPatches

@@ -279,6 +279,20 @@ from the list and queue it to 'pu', in order to make it easier for
 people play with it without having to pick up and apply the patch to
 their trees themselves.
 
+------------------------------------------------
+Know the status of your patch after submission
+
+* You can use Git itself to find out when your patch is merged in
+  master. 'git pull --rebase' will automatically skip already-applied
+  patches, and will let you know. This works only if you rebase on top
+  of the branch in which your patch has been merged (i.e. it will not
+  tell you if your patch is merged in pu if you rebase on top of
+  master).
+
+* Read the git mailing list, the maintainer regularly posts messages
+  entitled "What's cooking in git.git" and "What's in git.git" giving
+  the status of various proposed changes.
+
 ------------------------------------------------
 MUA specific hints