Add model card metadata

To help make your model more discoverable to domain experts, I suggest adding a `legal` tag to the metadata for your model.

README.md

@@ -2,6 +2,8 @@
 license: afl-3.0
 language:
 - it
+tags:
+- legal
 ---
 
 <img  src="https://huggingface.co/dlicari/lsg16k-Italian-Legal-BERT/resolve/main/ITALIAN_LEGAL_BERT-LSG.jpg" width="600"/>