doc:it_IT: add translations in process/

This patch adds the Italian translation for the following documents
in Documentation/process:

- applying-patches
- submit-checklist
- submitting-drivers
- changes
- stable api nonsense

Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>