Use `.huggingface.yaml` instead of embeded config in README

[adrinjalali]

There is a (probably undocumented) feature that one can use a .huggingface.yaml instead of embedding config in the README (internal private PR: https://github.com/huggingface/moon-landing/pull/6213 ).

We should use that as well, and cleanup our README generation.

cc @BenjaminBossan

[BenjaminBossan]

Sounds good. Let's wait until it's officially released.