Fix `license` metadata

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

Thanks! 🙏

README.md

@@ -1,6 +1,6 @@
 ---
 pretty_name: Korpus Malti
-languages:
+language:
 - mt
 multilinguality:
 - monolingual
@@ -18,7 +18,7 @@ task_categories:
 task_ids:
 - language-modeling
 - masked-language-modeling
-licenses:
+license:
 - cc-by-nc-sa-4.0
 ---
 # Korpus Malti 🇲🇹