media: docs: aspeed-video: Update reference

Use URL rather than plain text.
Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Documentation/userspace-api/media/drivers/aspeed-video.rst

@@ -23,7 +23,7 @@ proprietary mode.
 
 More details on the ASPEED video hardware operations can be found in
 *chapter 6.2.16 KVM Video Driver* of SDK_User_Guide which available on
-AspeedTech-BMC/openbmc/releases.
+`github <https://github.com/AspeedTech-BMC/openbmc/releases/>`__.
 
 The ASPEED video driver implements the following driver-specific control: