Update the load balancing cookbook
Update the load balancing cookbook

The "basic load balancing cookbook" still had a reference to
neutron-lbaas and an old DVR bug.
This patch corrects those issues.

Change-Id: I9299084402a0b09104e81f48e998b77a195745a0
Story: 2006470
Task: 36401

openstack/octavia,openstack/octavia,openstack/octavia