[gnome-boxes/update-docs: 8/17] help, docs: Add note that 3D Acceleration only works on Linux

[Felipe Borges <felipeborges src gnome org>]

commit 34bf49e85550c8f785d5a10d6929dc1bb8dc58b6
Author: Felipe Borges <felipeborges gnome org>
Date:   Wed Jan 5 11:50:20 2022 +0100

    help, docs: Add note that 3D Acceleration only works on Linux
    
    So far.

 help/C/3d-acceleration.page | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/help/C/3d-acceleration.page b/help/C/3d-acceleration.page
index ca6466e5..304d61b9 100644
--- a/help/C/3d-acceleration.page
+++ b/help/C/3d-acceleration.page
@@ -31,6 +31,10 @@
   your everyday graphic-hungry applications and games. It uses <sys>Virgil</sys> to create
   a virtual 3D capable graphics card for your QEMU virtual machines.</p>
 
+  <note style="info">
+    <p>Currently only Linux guests support 3D acceleration.</p>
+  </note>
+
   <steps>
     <title>To enable 3D Acceleration in a box:</title>
     <item><p>Right-click on the box in the collection view and select