Added missed vxlan network type and JavaDoc

apis/openstack-neutron/src/main/java/org/jclouds/openstack/neutron/v2/domain/NetworkType.java

@@ -18,7 +18,10 @@
 package org.jclouds.openstack.neutron.v2.domain;
 
 /**
- * Enumerates supported Network types.
+ * Enumerates supported Network types. 
+ * 
+ * @see <a href=
+ *      "http://docs.openstack.org/api/openstack-network/2.0/content/provider_ext.html">api doc</a>
  */
 public enum NetworkType {
    /**
@@ -33,6 +36,18 @@ public enum NetworkType {
     * Used to describe a VLAN network. NetworkSegment might have to be set.
     */
    VLAN("vlan"),
+   /**
+    * Used to describe a Virtual Extensible LAN (VXLAN) network. 
+    * It uses a VLAN-like encapsulation technique to encapsulate MAC-based 
+    * OSI layer 2 Ethernet frames within layer 4 UDP packets.
+    */
+   VXLAN("vxlan"),
+   /**
+    * Used to describe a GRE tunnel network. A virtual network realized as 
+    * packets encapsulated using Generic Routing Encapsulation. GRE tunnel 
+    * packets are routed by the compute node hosts, so GRE tunnels are not 
+    * associated by the openvswitch plugin with specific physical networks.
+    */
    GRE("gre"),
    /**
     * Used by jclouds when the service returns an unknown value other than null.