Add pipeline tag and library_name to model card

This PR enhances the model card by:
- Adding the `pipeline_tag: text-generation` to improve discoverability for code generation tasks on the Hugging Face Hub (e.g., at https://huggingface.co/models?pipeline_tag=text-generation).
- Specifying `library_name: transformers` in the metadata. This enables the automated "how to use" widget on the model page, providing a convenient code snippet for users, as the model's `config.json` indicates compatibility with `transformers` (e.g., `model_type: qwen2`, `architectures: ["Qwen2ForCausalLM"]`).

README.md

@@ -1,8 +1,11 @@
 ---
-license: apache-2.0
 language:
 - en
+license: apache-2.0
+pipeline_tag: text-generation
+library_name: transformers
 ---
+
 ## Alignment with Fill-In-the-Middle for Enhancing Code Generation
 
 <p align="center">