Documentation: add note block surrounding security patch note

Security patches have different handling than rest of patches for
review.

Enclose note paragraph about such patches in `.. note::` block.

Cc: Sasha Levin <sashal@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20220314113329.485372-2-bagasdotme@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>