Italian/model sharing (#17828)

* Add Italian translation of the doc file model_sharing.mdx

* Fix style

* Fix typo

* Update docs/source/it/_toctree.yml

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

docs/source/it/_toctree.yml

@@ -15,6 +15,8 @@
     title: Preprocess
   - local: training
     title: Mettere a punto un modello pre-addestrato
+  - local: model_sharing
+    title: Condividere un modello
   title: Esercitazione
 - sections:
   - local: run_scripts