Extend virtio-gpu documentation with a link to the Mesa VirGL
documentation.

Suggested-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
---
 docs/system/devices/virtio-gpu.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/docs/system/devices/virtio-gpu.rst b/docs/system/devices/virtio-gpu.rst
index f20c60016376..f8963c1f13cf 100644
--- a/docs/system/devices/virtio-gpu.rst
+++ b/docs/system/devices/virtio-gpu.rst
@@ -59,7 +59,7 @@ on typical modern Linux distributions.
 virtio-gpu virglrenderer
 ------------------------
 
-When using virgl accelerated graphics mode in the guest, OpenGL API calls
+When using `virgl`_ accelerated graphics mode in the guest, OpenGL API calls
 are translated into an intermediate representation (see `Gallium3D`_). The
 intermediate representation is communicated to the host and the
 `virglrenderer`_ library on the host translates the intermediate
@@ -68,6 +68,7 @@ representation back to OpenGL API calls.
 .. parsed-literal::
     -device virtio-gpu-gl
 
+.. _virgl: https://docs.mesa3d.org/drivers/virgl.html
 .. _Gallium3D: https://www.freedesktop.org/wiki/Software/gallium/
 .. _virglrenderer: https://gitlab.freedesktop.org/virgl/virglrenderer/
 
-- 
2.48.1