docs: add a .pylintrc file with sys path for docs scripts

The docs scripts that are used by Documentation/sphinx are
using scripts/lib/* directories to place classes that will
be used by both extensions and scripts.

When pylint is used, it needs to identify the path where
such scripts are, otherwise it will bail out. Add a simple
RC file placing the location of such files.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/7b3c8a932c50ae52ce4c848676602b46d1d4a8f9.1744106242.git.mchehab+huawei@kernel.org