Documentation/amdgpu: fix 'in the amdgfx' formulation

Clarify the mailing list.

Signed-off-by: Yann Dirson <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

Documentation/gpu/amdgpu/display/dc-glossary.rst

···
 On this page, we try to keep track of acronyms related to the display
 component. If you do not find what you are looking for, look at the
 'Documentation/gpu/amdgpu/amdgpu-glossary.rst'; if you cannot find it anywhere,
-consider asking in the amdgfx and update this page.
+consider asking on the amd-gfx mailing list and update this page.
 
 .. glossary::
 

Documentation/gpu/amdgpu/display/display-contributing.rst

···
 
 This page summarizes some of the issues you can help with; keep in mind that
 this is a static page, and it is always a good idea to try to reach developers
-in the amdgfx or some of the maintainers. Finally, this page follows the DRM
-way of creating a TODO list; for more information, check
+on the amd-gfx mailing list or some of the maintainers. Finally, this page
+follows the DRM way of creating a TODO list; for more information, check
 'Documentation/gpu/todo.rst'.
 
 Gitlab issues