docs(pixtral): Update Pixtral model card to new format

[BryanBradfo]

What does this PR do?

This pull request updates the pixtral.md model card to align with the new standardized format, as requested in issue #36979.

The main changes include:

• Restructuring the document to follow the new standard layout (header, description, tip, hfoptions).
• Simplifying the model's description to be more accessible.
• Setting up the hfoptions block with the AutoModel code example from the previous documentation.

A Note on Code Validation

I have done my best to prepare the AutoModel code example based on the existing documentation. However, due to hardware limitations (the Pixtral-12B model is too large for my local machine), I was unable to run and personally verify that this code works as expected with the latest transformers version.

Could a reviewer with the necessary computing resources please check if the AutoModel example runs correctly? Any help in adding the Pipeline and transformers-cli examples would also be greatly appreciated.

This PR is a starting point, and I'm eager to learn from your feedback to complete it.

Fixes #36979

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline,
  Pull Request section?
• Was this discussed/approved via a Github issue or the forum? Please add a link
  to it if that's the case.
• Did you make sure to update the documentation with your changes? Here are the
  documentation guidelines, and
  here are tips on formatting docstrings.
• Did you write any new necessary tests?

Who can review?

Based on the contribution guide for documentation: cc @stevhliu

[stevhliu]

Thanks!

[stevhliu]

Just a few more minor things and then we can merge :)

[BryanBradfo]

Thanks!

I am glad I can help and be useful 🤗

[BryanBradfo]

Just a few more minor things and then we can merge :)

It was what I was thinking about! That's done! I've moved the image as requested. Let me know whether it's good now!

[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.