Update model release checklist

[merveenoyan]

Added some best practices for things I come across that model publishers don't follow

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[Vaibhavs10]

feels a bit out of place in the pipeline tag section, specially so we talk about it here:

https://huggingface.co/docs/hub/en/model-release-checklist#writing-a-comprehensive-model-card

[merveenoyan]

@Vaibhavs10 I see sooooo many models with missing licenses I think most basic info should be license + task tag. it's even worse because we don't know the license itself that we can't open PR, the author has to do it themselves. and this page sits right after /new so it's best to have licenses.