Move create network section to the bottom

Locate Create the base Neutron networks section after the sections
involving installation of Neutron on the network, controller, and
compute nodes, which makes the order more sense.

Change-Id: I9229324c2f9eac6a324f51e7d3dd853f17199fab
backport: havana
Closes-Bug: #1252334
Merge "Move create network section to the bottom"