Add paper link and improve model card metadata

This PR improves the model card for **RexDrug-base** by:
- Adding the `pipeline_tag: text-generation` metadata.
- Linking the model to the original research paper: [RexDrug: Reliable Multi-Drug Combination Extraction through Reasoning-Enhanced LLMs](https://huggingface.co/papers/2603.08166).
- Including a link to the official GitHub repository for source code and data.

These changes help improve the discoverability of the model and provide users with the necessary context for its research application.

README.md

@@ -1,19 +1,24 @@
 ---
-license: llama3.1
 base_model: meta-llama/Llama-3.1-8B-Instruct
 library_name: transformers
+license: llama3.1
+pipeline_tag: text-generation
 tags:
-  - drug-combination
-  - relation-extraction
-  - biomedical
-  - llama
-  - chain-of-thought
+- drug-combination
+- relation-extraction
+- biomedical
+- llama
+- chain-of-thought
 ---
 
 # RexDrug-Base
 
 This is the SFT (Supervised Fine-Tuning) base model for **RexDrug**, a chain-of-thought reasoning model for biomedical drug combination relation extraction.
 
+For more details, please refer to the paper: [RexDrug: Reliable Multi-Drug Combination Extraction through Reasoning-Enhanced LLMs](https://huggingface.co/papers/2603.08166).
+
+**Official Code:** [DUTIR-BioNLP/RexDrug](https://github.com/DUTIR-BioNLP/RexDrug)
+
 ## Model Details
 
 - **Base architecture**: [Llama-3.1-8B-Instruct](https://huggingface.co/meta-llama/Llama-3.1-8B-Instruct)
@@ -40,4 +45,4 @@ model = PeftModel.from_pretrained(model, "dlutIR/RexDrug-adapter")
 
 ## License
 
-This model is built upon Llama 3.1 and is subject to the [Llama 3.1 Community License Agreement](https://github.com/meta-llama/llama-models/blob/main/models/llama3_1/LICENSE).
+This model is built upon Llama 3.1 and is subject to the [Llama 3.1 Community License Agreement](https://github.com/meta-llama/llama-models/blob/main/models/llama3_1/LICENSE).