mistralai/Voxtral-Small-24B-2507 · Improve model card: Update library, add paper link, abstract summary, and refine tags

This PR significantly enhances the model card for Voxtral Small by:

Updating the library_name from vllm to transformers in the metadata, as the model is natively supported and has extensive usage examples for the Hugging Face transformers library. This ensures proper functionality of the "how to use" widget on the Hub.
Adding vllm to the tags in the metadata to maintain discoverability and highlight its recommended use for serving.
Removing the inference: false metadata tag, as the model provides comprehensive usage instructions, indicating it is ready for inference.
Adding a direct link to the paper "Voxtral" prominently in the introductory section.
Including a concise summary of the paper's abstract at the top of the model card content for immediate understanding of the model's capabilities and contributions.