[Koha-translate] Update of manual translation (3.18 and 3.20 italian)

Hi to all, Is it possible to update 3.18 manual it_IT ? We have done much work on .po files and we hope to show it. As italian user we ask to add it_iT to 3.20 manual. Now we are using 3.20 and we want to complete transaltion on this version. Bye Zeno Tajoli