doc:it_IT: align Italian documentation

Translation for the following patches

commit da4288b9 ("scripts/check-local-export: avoid 'wait $!' for process substitution")
commit 5372de4e ("docs/doc-guide: Put meta title for kernel-doc HTML page")
commit 4d627ef1 ("docs/doc-guide: Mention make variable SPHINXDIRS")
commit 7c43214d ("docs/doc-guide: Add footnote on Inkscape for better images in PDF documents")
commit 615041d4 ("docs: kernel-docs: shorten the lengthy doc title")
commit cbf4adfd ("Documentation: process: Update email client instructions for Thunderbird")
commit e72b3b98 ("maintainer-pgp-guide: minor wording tweaks")
commit ea522496 ("Documentation: process: replace outdated LTS table w/ link")
commit 93431e06 ("Replace HTTP links with HTTPS ones: documentation")
commit e648174b ("Documentation: Fix spelling mistake in hacking.rst")
commit 602684ad ("docs: Update version number from 5.x to 6.x in README.rst")
commit 48987606 ("docs: add a man-pages link to the front page")
commit 0c7b4366 ("docs: Rewrite the front page")

Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Link: https://lore.kernel.org/r/20221231130849.4675-1-federico.vaga@vaga.pv.it


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