contributor-guide: submit-changes: how to request push access to repositories

Including content currently on
http://www.openembedded.org/wiki/How_to_submit_a_patch_to_OpenEmbedded

(From yocto-docs rev: 34b22fd3c48d55bcddbf725395f9ee4e389ae354)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/contributor-guide/submit-changes.rst

@@ -502,9 +502,18 @@ have been followed:
    in the
    `Git Community Book <https://git-scm.com/book/en/v2/Distributed-Git-Distributed-Workflows>`__.
 
-#. *Push Your Commits to a "Contrib" Upstream:* If you have arranged for
-   permissions to push to an upstream contrib repository, push the
-   change to that repository::
+#. *Request Push Access to an "Upstream" Contrib Repository:* Send an email to
+   ``helpdesk@yoctoproject.org``:
+
+    -  Attach your SSH public key which usually named ``id_rsa.pub.``.
+       If you don't have one generate it by running ``ssh-keygen -t rsa -b 4096 -C "your_email@example.com"``.
+
+    -  List the repositories you're planning to contribute to.
+
+    -  Include your preferred branch prefix for ``-contrib`` repositories.
+
+#. *Push Your Commits to the "Contrib" Upstream:* Push your
+   changes to that repository::
 
       $ git push upstream_remote_repo local_branch_name