[PATCH] doc: gpu: drm-internals: Create reference to DRM mm

[Markus Schneider-Pargmann <msp@baylibre.com>]

This short sentence references nothing for details about memory manager.
Replace it with the documentation file for DRM memory management.

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
 Documentation/gpu/drm-internals.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/gpu/drm-internals.rst b/Documentation/gpu/drm-internals.rst
index 06af044c882f..bdcdfc4ede04 100644
--- a/Documentation/gpu/drm-internals.rst
+++ b/Documentation/gpu/drm-internals.rst
@@ -126,8 +126,8 @@ Memory Manager Initialization
 Every DRM driver requires a memory manager which must be initialized at
 load time. DRM currently contains two memory managers, the Translation
 Table Manager (TTM) and the Graphics Execution Manager (GEM). This
-document describes the use of the GEM memory manager only. See ? for
-details.
+document describes the use of the GEM memory manager only. See
+Documentation/gpu/drm-mm.rst for details.
 
 Miscellaneous Device Configuration
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- 
2.33.0