Align with Croissant for dataset descriptions

[elichad]

It should be possible to include Croissant JSON-LD in the crate with just a little bit of processing.

[elichad]

Should existing Croissant metadata (e.g. https://huggingface.co/api/datasets/uoft-cs/cifar10/croissant) be added to the crate directly? Or can/should it be referenced - if so what is a good term to reference it through?