Librarian Bot: Add language metadata for dataset (#2)

- Librarian Bot: Add language metadata for dataset (afc7649d55ee4a38090caecbade9c313d5beb93c)


Co-authored-by: Librarian Bot (Bot) <librarian-bot@users.noreply.huggingface.co>

README.md

@@ -1,3 +1,5 @@
 ---
+language:
+- ja
 license: cc-by-nc-nd-4.0
 ---