Improve model card: add metadata, paper link, and base model reference

Hi! I'm Niels, part of the community science team at Hugging Face.

This pull request aims to improve the model card for **Qwen2.5-Coder-0.5B-Instruct-diffusion-mdlm-v0.1**. I have added YAML metadata for `pipeline_tag`, `library_name`, and `base_model` to make the model easier to find and use. I've also added an explicit link to the **dLLM** paper and maintained the existing codebase references.

These changes help users identify the model's lineage and provide quick access to the associated research and framework.

README.md

@@ -1,5 +1,12 @@
 ---
 license: apache-2.0
+library_name: transformers
+base_model: Qwen/Qwen2.5-Coder-0.5B-Instruct
+pipeline_tag: text-generation
+tags:
+- code
+- diffusion-lm
+- mdlm
 ---
 
 <center> <div style="text-align: center;"> <img src="https://raw.githubusercontent.com/ZHZisZZ/dllm/main/assets/logo.gif" width="400" />
@@ -7,7 +14,7 @@ license: apache-2.0
 
 # Qwen2.5-Coder-0.5B-Instruct-diffusion-mdlm-v0.1
 
-Qwen2.5-Coder-0.5B-Instruct-diffusion-mdlm-v0.1 is a diffusion-based language model adapted from [Qwen2.5-Coder-0.5B-Instruct](https://huggingface.co/Qwen/Qwen2.5-Coder-0.5B-Instruct) using [MDLM](https://arxiv.org/abs/2406.07524) (masked diffusion), trained with the [dLLM](https://github.com/ZHZisZZ/dllm) framework.
+Qwen2.5-Coder-0.5B-Instruct-diffusion-mdlm-v0.1 is a diffusion-based language model adapted from [Qwen2.5-Coder-0.5B-Instruct](https://huggingface.co/Qwen/Qwen2.5-Coder-0.5B-Instruct) using [MDLM](https://arxiv.org/abs/2406.07524) (masked diffusion). It was trained using the [dLLM](https://github.com/ZHZisZZ/dllm) framework, as presented in the paper [dLLM: Simple Diffusion Language Modeling](https://huggingface.co/papers/2602.22661).
 
 
 ## Model Overview
@@ -165,7 +172,8 @@ new_tokens = [
     text[i, prompt_lens[i] : prompt_lens[i] + max_new_tokens].tolist() for i in range(text.size(0))
 ]
 for idx, decoded in enumerate(tokenizer.batch_decode(new_tokens, skip_special_tokens=False)):
-    print(f"\n[Sample {idx}]")
+    print(f"
+[Sample {idx}]")
     print(decoded)
 
 ```
@@ -251,4 +259,4 @@ If you use Qwen2.5-Coder-0.5B-Instruct-diffusion-mdlm-v0.1 or dLLM, please cite:
       primaryClass={cs.CL},
       url={https://arxiv.org/abs/2602.22661}, 
 }
-```
+```