[3389a] Minor improvement in the docs

doc/guide/dhcp6-srv.xml

@@ -629,9 +629,20 @@ temporarily override a list of interface names and listen on all interfaces.
   <para>As for the DHCPv4 server binding to specific addresses and
   disabling re-detection of interfaces are supported. But
   <command>dhcp-socket-type</command> is not because DHCPv6 uses
-  UDP/IPv6 sockets only.
+  UDP/IPv6 sockets only. The following example shows how to disable the
+  interface detection:
   </para>
 
+  <screen>
+"Dhcp6": {
+    "interfaces-config": {
+        "interfaces": [ <userinput>"eth1", "eth3"</userinput> ],
+        "re-detect": <userinput>false</userinput>
+    },
+    ...
+}
+  </screen>
+
 </section>
 
     <section id="ipv6-subnet-id">