Fix `license` metadata

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

Thanks! 🙏

README.md

@@ -1,9 +1,9 @@
 ---
 annotations_creators: []
 language_creators: []
-languages:
+language:
 - cz, de, it
-licenses: []
+license: []
 multilinguality:
 - translation
 pretty_name: merlin