Add few more guidelines for submitting patches:
- encourage use of checkpatch.pl script from Linux kernel
- add guide for good subject for a patch
- add links to guides about how to create a good patch
- add guide for responding to CI failure letters

v1: expand patch from Louis on checkpatch,
  also take a hint from Jani about checkpatch options
  add a guide for checking test results from CI
  correct 'typdef' to 'typedef' (Zbigniew)

Cc: Arthur Grillo <arthurgrillo@riseup.net>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Cc: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Cc: Katarzyna Piecielska <katarzyna.piecielska@intel.com>
Cc: Louis Chauvet <louis.chauvet@bootlin.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Petri Latvala <adrinael@adrinael.net>
Cc: "Zbigniew Kempczyński" <zbigniew.kempczynski@intel.com>
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin....>