Update README.md

For indexation in the leaderboard finder : https://huggingface.co/spaces/OpenEvals/find-a-leaderboard (you can add more tags following the "how to" if you want)

README.md

@@ -9,6 +9,8 @@ pinned: true
 license: apache-2.0
 short_description: Duplicate this leaderboard to initialize your own!
 sdk_version: 5.19.0
+tags:
+  - leaderboard
 ---
 
 # Start the configuration