Fix `license` metadata

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

Thanks! 🙏

README.md

@@ -5,7 +5,7 @@ language_creators:
 - found
 - machine-generated
 - expert-generated
-languages:
+language:
 - bn-hi
 - cs-en
 - de-en
@@ -26,7 +26,7 @@ languages:
 - xh-zh
 - zh-en
 - zu-xh
-licenses:
+license:
 - unknown
 multilinguality:
 - translation