Added warning for MTU value

Author: Shubha Narayanan

modules/nw-sriov-networknodepolicy-object.adoc

@@ -50,6 +50,11 @@ When specifying a name, be sure to use the accepted syntax expression `^[a-zA-Z0
 <5> Optional: The priority is an integer value between `0` and `99`. A smaller value receives higher priority. For example, a priority of `10` is a higher priority than `99`. The default value is `99`.
 
 <6> Optional: The maximum transmission unit (MTU) of the virtual function. The maximum MTU value can vary for different network interface controller (NIC) models.
++
+[IMPORTANT]
+====
+If you want to create virtual function on the default network interface, ensure that the MTU is set to a value that matches the cluster MTU.
+====
 
 <7> Optional: Set `needVhostNet` to `true` to mount the `/dev/vhost-net` device in the pod. Use the mounted `/dev/vhost-net` device with Data Plane Development Kit (DPDK) to forward traffic to the kernel network stack.