Fix `license` metadata

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

Thanks! 🙏

README.md

@@ -1,12 +1,12 @@
 ---
-licenses: 
+license: 
 - cc-by-4.0
 annotations_creators:
 - found
 - machine-generated
 language_creators:
 - found
-languages:
+language:
 - TypeScript
 multilinguality:
 - monolingual