Add releasing docs

Change-Id: I7eef91e7bc11a1470707919fc0081fbb2a6a4105

doc/source/index.rst

@@ -8,6 +8,7 @@ Contents:
 
    README
    drivers
+   releasing
 
 Indices and tables
 ==================

doc/source/releasing.rst

@@ -0,0 +1,38 @@
+Releasing ironic-staging-drivers
+================================
+
+This section is relevant to the maintainers of ironic-staging-drivers. You have
+to be a member of the ironic-staging-drivers-release_ group to do releases.
+
+#. Verify that the CI works via a dummy patch.
+
+#. Create a **signed** tag locally::
+
+       git tag -s -m "Release <version>" <version>
+
+#. Push the new tag to gerrit::
+
+       git push gerrit <version>
+
+#. Wait for the new release to appear on PyPI_, contact the infra team in case
+   of any issues.
+
+#. If a stable branch is needed, go to the *branches* section of the
+   `ironic-staging-drivers settings`_ in gerrit and add a new branch from the
+   newly created tag.
+
+#. If a stable branch has been created, submit a change for it that:
+
+   #. updates ``.gitreview`` with a new ``defaultbranch``,
+
+   #. updates ``extra-requirements.txt`` with a link to ironic stable,
+
+   #. updates ``tox.ini`` to use upper constraints from the corresponding
+      release.
+
+   See the `stable/xena patch`_ for an example.
+
+.. _ironic-staging-drivers-release: https://review.opendev.org/admin/groups/bf6b0cc8749d0d89a8620882f697a60b46f032ab
+.. _PyPI: https://pypi.org/project/ironic-staging-drivers/
+.. _ironic-staging-drivers settings: https://review.opendev.org/admin/repos/x/ironic-staging-drivers
+.. _stable/xena patch: https://review.opendev.org/c/x/ironic-staging-drivers/+/810657