Added upgrade note for separate nova and cinder keys.

Closes-Bug: 1928690
Change-Id: I1bf7c272c782134511e6553a1e2a4b7220556802

Author: abraden

doc/source/user/operating-kolla.rst

@@ -65,6 +65,12 @@ Limitations and Recommendations
    ``"yes"``, you need to have the ``log_bin_trust_function_creators`` set to
    ``1`` by your database administrator before performing the upgrade.
 
+.. note::
+
+   If you have separate keys for nova and cinder, please be sure to set
+   ``ceph_nova_keyring: ceph.client.nova.keyring`` and ``ceph_nova_user: nova``
+   in ``/etc/kolla/globals.yml``
+
 Ubuntu Focal 20.04
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