Add chapter for HA virtualization (#361)

* Initial chapter creation

* Filled out chapter after testing

* Change intro markup

* Adjust VM resource section to account for multiple VMs

* Other tech review updates

* Update resource names to match admin guide naming conventions

xml/book_administration.xml

@@ -66,6 +66,7 @@
   <xi:include href="ha_acl.xml"/>
   <xi:include href="ha_netbonding.xml"/>
   <xi:include href="ha_loadbalancing.xml"/>
+  <xi:include href="ha_virtualization.xml"/>
   <xi:include href="ha_geocluster.xml"/>
  </part>