docs: change the title of networking docs

The current title of our section of the documentation is
Linux Networking Documentation. Since we're describing
a section of Linux Documentation repeating those two
words seems redundant.

Link: https://lore.kernel.org/r/20220518234346.2088436-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/index.rst

@@ -1,5 +1,5 @@
-Linux Networking Documentation
-==============================
+Networking
+==========
 
 Refer to :ref:`netdev-FAQ` for a guide on netdev development process specifics.