Update README.md

Re-upload updated metadata.json for v0.5.2

Re-upload updated audit.json with correct SHA256 hashes

Temp: remove stale metadata.json

Temp: remove stale audit.json

Upload metadata.json with huggingface_hub

Fix SHA256 hashes for augmented train.jsonl

v0.5.2: augmented negatives 800 + multi-call 440, train 5046 rows, 0 overlength

initial commit