Add OVN principle charms to the charm/OpenStack upgrade order

This is also the way we'll be validating upgrade with
our automated tests:
https://github.com/openstack-charmers/zaza-openstack-tests/pull/655

Change-Id: If462faad3f21dd6ae9730e0ccc28b4cb8d8a8b71

deploy-guide/source/upgrade-charms.rst

@@ -102,7 +102,7 @@ table.
      - `neutron-api`_
 
    * - 19
-     - `neutron-gateway`_
+     - `neutron-gateway`_ or `ovn-central`_
 
    * - 20
      - `placement`_
@@ -117,12 +117,15 @@ table.
      - `nova-compute`_
 
    * - 24
-     - `ceph-osd`_
+     - `ovn-dedicated-chassis`_
 
    * - 25
-     - `swift-proxy`_
+     - `ceph-osd`_
 
    * - 26
+     - `swift-proxy`_
+
+   * - 27
      - `swift-storage`_
 
 Upgrade testing for subordinate charms does not follow a prescribed order. Once

deploy-guide/source/upgrade-openstack.rst

@@ -224,7 +224,7 @@ The order provided below is the order used by internal testing.
      - `neutron-api`_
 
    * - 18
-     - `neutron-gateway`_
+     - `neutron-gateway`_ or `ovn-central`_
 
    * - 19
      - `placement`_
@@ -239,15 +239,18 @@ The order provided below is the order used by internal testing.
      - `nova-compute`_
 
    * - 23
-     - `ceph-osd`_
+     - `ovn-dedicated-chassis`_
 
    * - 24
-     - `swift-proxy`_
+     - `ceph-osd`_
 
    * - 25
-     - `swift-storage`_
+     - `swift-proxy`_
 
    * - 26
+     - `swift-storage`_
+
+   * - 27
      - `octavia`_
 
 .. important::