docs: Create translations/sp_SP/process/, move submitting-patches.rst

The organization of the Spanish translations should be consistent with the
rest of kernel documentation. Create directory process/ and move
submitting-patches.rst there. Update indexes accordingly.

Signed-off-by: Carlos Bilbao <carlos.bilbao@amd.com>
Link: https://lore.kernel.org/r/20221124170242.1892751-5-carlos.bilbao@amd.com


Signed-off-by: Jonathan Corbet <corbet@lwn.net>