Update the "Create Flavor" screen to the latest

The "Create Flavor" screen miss "RX/TX Factor", so update is to the latest,
and add the miss item to the table list.

Change-Id: I7fcb5dc37b913a937abac9fc27e9286b4c882984

doc/admin-guide/source/dashboard_manage_flavors.rst

@@ -59,6 +59,12 @@ Create flavors
     **Swap Disk (MB)**         Enter the amount of swap space (in
                                megabytes) to use. If unspecified,
                                the default is 0.
+    **RX/TX Factor**           Optional property allows servers with
+                               a different bandwidth to be created
+                               with the RX/TX Factor. The default
+                               value is 1. That is, the new bandwidth
+                               is the same as that of the attached
+                               network.
    =========================  =======================================
 
 #. In the :guilabel:`Flavor Access` tab, you can control access to