Add OVN support

Install docs:
https://docs.openstack.org/networking-ovn/latest/install/index.html

Partial Prod: PROD-15003

Co-Authored-By: Elena Ezhova <eezhova@mirantis.com>
Change-Id: I0a7023f3e14aae6d5ec5efe8f117ebc9d0ed302d
diff --git a/README.rst b/README.rst
index 3b161e5..57153ed 100644
--- a/README.rst
+++ b/README.rst
@@ -591,6 +591,7 @@
               driver: openvswitch
 
 Advanced Neutron Features (DPDK, SR-IOV)
+----------------------------------------
 
 Neutron OVS DPDK
 
@@ -648,6 +649,7 @@
               driver: openvswitch
 
 Neutron with VLAN-aware-VMs
+---------------------------
 
 .. code-block:: yaml
 
@@ -661,6 +663,34 @@
       gateway:
         vlan_aware_vms: true
 
+Neutron with OVN
+----------------
+
+Control node:
+
+.. code-block:: yaml
+
+    neutron:
+      server:
+        backend:
+          engine: ovn
+          mechanism:
+            ovn:
+              driver: ovn
+          tenant_network_types: "geneve,flat"
+
+Compute node:
+
+.. code-block:: yaml
+
+    neutron:
+      compute:
+        local_ip: 10.2.0.105
+        controller_vip: 10.1.0.101
+        external_access: false
+        backend:
+          engine: ovn
+
 Neutron Server
 --------------
 
@@ -692,7 +722,6 @@
           user: admin
           password: password
 
-
 Neutron Keystone region
 
 .. code-block:: yaml