doc: update s5 document

For WaaG VM, the User VM name is hard coded in the
lifecycle manager, this User VM ("windows") is needed
for guest shutdown.
Note: libvirt will be used to do guest shutdown and
the WaaG VM name will be configurable in furture.

The lifecycle manager starup picture in WaaG VM is out
of data, update it in this patch.

Tracked-on: #6652
Signed-off-by: Xiangyang Wu <xiangyang.wu@intel.com>

doc/tutorials/enable_s5.rst

@@ -290,6 +290,7 @@ How to Test
       sudo python3 ~/user_vm_shutdown.py <User VM name>
 
    .. note:: The User VM name is configured in the :file:`life_mngr.conf` of User VM.
+      For the WaaG VM, the User VM name is "windows".
 
 #. Use the ``acrnctl list`` command to check the User VM status.