Fix Dataset Viewer: remove all non-JSONL JSON files
ismail.tasdelen
8521039
HF worker scans all JSON files in repo and tries to cast them to dataset
schema, causing CastError. Renamed all non-JSONL JSON files to .txt:
- manifest.json → manifest.txt
- statistics/summary.json → statistics/summary.txt
- evaluation/rubrics/rubric_v1.json → evaluation/rubrics/rubric_v1.txt
- validation/validation_summary.json → validation/validation_summary.txt
Also removed dataset_info from README.md and added .hfignore.
