Fix `license` metadata

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

Thanks! 🙏

README.md

@@ -2,8 +2,8 @@ image-classification
 ---
 annotations_creators: []
 language_creators: []
-languages: []
-licenses: []
+language: []
+license: []
 multilinguality:
 - monolingual
 pretty_name: airplanes