doc:it_IT: documentation alignment

It aligns the italian translation with the latest changes:

ae67ee6c docs: fix Co-Developed-by docs
3fe5dbfe Documentation/process/coding-style.rst: don't use "extern" with function prototypes

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