docs: kernel-hacking: hacking.rst: avoid using ReST :doc:`foo` markup

The :doc:`foo` tag is auto-generated via automarkup.py.
So, use the filename at the sources, instead of :doc:`foo`.

Signed-off-by: Mauro Carvalho Chehab <[email protected]>
Link: https://lore.kernel.org/r/9537b74d897fab13552535d79337060a3b241b8c.1623824363.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <[email protected]>
1 file changed