LLM4Code/CodeARC_anonymous_llama3.1 · Improve model card with metadata, abstract, and sample usage

This PR significantly improves the model card for the CodeARC model by:

Adding the pipeline_tag: text-generation to the metadata, which ensures the model can be easily discovered on the Hugging Face Hub (e.g., at https://huggingface.co/models?pipeline_tag=text-generation).
Specifying the library_name: transformers in the metadata, making it clear which library is compatible with this model and enabling direct loading with the transformers library.
Including the paper's abstract in the model card content for a concise overview of the research.
Adding a practical "Sample Usage" section, extracted from the GitHub repository's README, to guide users on how to quickly set up and run the model.

These changes enhance the discoverability, usability, and informative nature of the model card.