[gnome-boxes] help: Add step to restart a running VM to enable 3D Acceleration.

[Felipe Borges <felipeborges src gnome org>]

commit 814ecc1221bdd2b64ec8743bd3b20c5bbd7e3f57
Author: Pranali Deshmukh <pranali21293 gmail com>
Date:   Wed Oct 7 00:44:40 2020 +0530

    help: Add step to restart a running VM to enable 3D Acceleration.
    
    Add a final step to the 3D Acceleration documentation to mention that enable
    3D Acceleration, running virtual machines need to be restarted.
    
    Ref: #611, #382

 help/C/3d-acceleration.page | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/help/C/3d-acceleration.page b/help/C/3d-acceleration.page
index cf7251d4..50227284 100644
--- a/help/C/3d-acceleration.page
+++ b/help/C/3d-acceleration.page
@@ -41,6 +41,9 @@
     <item><p>If 3D Acceleration is supported, the <gui>3D Acceleration</gui> switch would 
     appear here. By default, it is disabled. To enable 3D Acceleration, simply toggle the 
     switch next to it to <gui style="switch">ON</gui>.</p></item>
+    <item><p>In case the virtual machine for which 3D Acceleration has just been enabled is 
+    already running, then, Boxes will show a notification asking to restart the running
+    virtual machine.</p></item>
   </steps>
 
 </page>