docs: networking: devlink: 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: NMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/4553858bc9a5442eba6d71caff8047e84ece4d9b.1623824363.git.mchehab+huawei@kernel.orgSigned-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/networking/devlink/devlink-region.rst

@@ -22,7 +22,7 @@ The major benefit to creating a region is to provide access to internal
 address regions that are otherwise inaccessible to the user.
 
 Regions may also be used to provide an additional way to debug complex error
-states, but see also :doc:`devlink-health`
+states, but see also Documentation/networking/devlink/devlink-health.rst
 
 Regions may optionally support capturing a snapshot on demand via the
 ``DEVLINK_CMD_REGION_NEW`` netlink message. A driver wishing to allow

Documentation/networking/devlink/devlink-trap.rst

@@ -495,8 +495,8 @@ help debug packet drops caused by these exceptions. The following list includes
 links to the description of driver-specific traps registered by various device
 drivers:
 
-  * :doc:`netdevsim`
-  * :doc:`mlxsw`
+  * Documentation/networking/devlink/netdevsim.rst
+  * Documentation/networking/devlink/mlxsw.rst
 
 .. _Generic-Packet-Trap-Groups: