MES is an important firmware that lacks some essential documentation.
This commit introduces an overview of it and how it works.

Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Rodrigo Siqueira <siqueira@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

GC is a large block that plays a vital role for amdgpu; for this reason,
this commit creates one specific page for GC and adds extra information
about the CP component.

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Rodrigo Siqueira <siqueira@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>