fix missing VLAN id for Qbg example

For IEEE 802.1Qbg, it is necessary to use a VLAN interface.
vepa itself does not require a VLAN interface.

Signed-off-by: Gerhard Stenzel <stenzel at de.ibm.com>

docs/formatdomain.html.in

@@ -1440,6 +1440,10 @@
       the Virtual Station Interface (VSI) represents the virtual interface
       of a virtual machine.
     </p>
+    <p>
+      Please note that IEEE 802.1Qbg requires a non-zero value for the
+      VLAN ID.
+    </p>
     <dl>
       <dt><code>managerid</code></dt>
       <dd>The VSI Manager ID identifies the database containing the VSI type
@@ -1466,7 +1470,7 @@
     &lt;interface type='direct'/&gt;
     ...
     &lt;interface type='direct'&gt;
-      &lt;source dev='eth0' mode='vepa'/&gt;
+      &lt;source dev='eth0.2' mode='vepa'/&gt;
       &lt;virtualport type="802.1Qbg"&gt;
         &lt;parameters managerid="11" typeid="1193047" typeidversion="2" instanceid="09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f"/&gt;
       &lt;/virtualport&gt;