Unhardcode more options for dhcp agent

Change-Id: I4e0ff6f5a77a012d5e2bd5d52a24e3574bf98df9
diff --git a/README.rst b/README.rst
index 4d3e86a..4c4bb32 100644
--- a/README.rst
+++ b/README.rst
@@ -211,7 +211,6 @@
         version: mitaka
         dhcp_lease_duration: 600
         firewall_driver: iptables_hybrid
-        ovs_use_veth: False
         message_queue:
           engine: rabbitmq
           host: 127.0.0.1
@@ -231,6 +230,9 @@
           mechanism:
             ovs:
               driver: openvswitch
+        agents:
+          dhcp:
+            ovs_use_veth: False
 
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