Add upgrade host configure warning for ceph nodes

Author: Alex-Welsh

doc/source/operations/upgrading-openstack.rst

@@ -971,6 +971,12 @@ would be applied:
 When ready to apply the changes, it may be advisable to do so in batches, or at
 least start with a small number of hosts.:
 
+.. warning::
+
+   Take extra care when configuring ceph hosts. Always reconfigure hosts in
+   small batches or one-by-one. Check the Ceph state after each host
+   configuration. Ensure all warnings and errors are resolved before moving on.
+
 .. code-block:: console
 
    kayobe overcloud host configure --limit <host>