Model card metadata documentation and specifications moved to https://github.com/huggingface/huggingface_hub/

The canonical documentation about model cards is now located at https://huggingface.co/docs/hub/model-repos and you can open a PR to improve the docs in the same repository https://github.com/huggingface/huggingface_hub/tree/main/docs/hub

You can also find a spec of the metadata at https://github.com/huggingface/huggingface_hub/blob/main/README.md.