Handle ovs_use_veth option

Change-Id: I3331ddae9840d9b1ae3dc07e4065684fbb1ab15f
Closes-Bug: PROD-21373
diff --git a/README.rst b/README.rst
index 7e63a20..34d660e 100644
--- a/README.rst
+++ b/README.rst
@@ -211,6 +211,7 @@
         version: mitaka
         dhcp_lease_duration: 600
         firewall_driver: iptables_hybrid
+        ovs_use_veth: False
         message_queue:
           engine: rabbitmq
           host: 127.0.0.1