Add REFUTE benchmark / leaderboard links?

[connerlambden]

Request to index:

• Dataset: https://huggingface.co/datasets/BGPT-OFFICIAL/refute
• Leaderboard: https://huggingface.co/spaces/BGPT-OFFICIAL/refute-leaderboard
• Inspect adapter: https://github.com/connerlambden/refute-inspect

Scientific critique & epistemic calibration benchmark.