F OpenNebula/one#6435: Add note about "auto" for VIRTIO_QUEUES in kvm

guide

(cherry picked from commit 67dbd7c)

Author: rsmontero

source/open_cluster_deployment/kvm_node/kvm_driver.rst

@@ -192,7 +192,7 @@ NIC
 
     $ virsh -c qemu:///system nwfilter-list
 
-* ``VIRTIO_QUEUES`` to define how many queues will be used for the communication between CPUs and Network drivers. This attribute is only available with ``MODEL="virtio"``.
+* ``VIRTIO_QUEUES`` to define how many queues will be used for the communication between CPUs and Network drivers. This attribute is only available with ``MODEL="virtio"``. The ``auto`` keyword automatically set the number of queues to the number of vCPUs.
 
 Graphics
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