Fix `license` metadata

We recently updated the datasets metadata for consistency with other repo types (models & spaces)

Thanks! 🙏

README.md

@@ -5,9 +5,9 @@ annotations_creators:
 language_creators:
 - found
 - expert-generated
-languages:
+language:
 - hu
-licenses:
+license:
 - bsd-2-clause
 multilinguality:
 - monolingual