Improve pipeline tag and add link to code

This PR improves the model card by changing the `pipeline_tag` to `text-generation` and adding a link to the Github repository.

README.md

@@ -1,20 +1,22 @@
 ---
-license: mit
+base_model:
+- Qwen/Qwen3-4B-Base
 datasets:
 - RuleReasoner/rule-reasoning
 language:
 - en
+library_name: transformers
+license: mit
 metrics:
 - accuracy
-base_model:
-- Qwen/Qwen3-4B-Base
-new_version: RuleReasoner/RuleReasoner-4B
-pipeline_tag: question-answering
-library_name: transformers
+pipeline_tag: text-generation
 tags:
 - rule-based reasoning
+new_version: RuleReasoner/RuleReasoner-4B
 ---
+
 If you use the model in your research, please cite the original papers as below.
+
 ```latex
 @article{liu2025rulereasoner,
       title={RuleReasoner: Reinforced Rule-based Reasoning via Domain-aware Dynamic Sampling}, 
@@ -25,4 +27,6 @@ If you use the model in your research, please cite the original papers as below.
       primaryClass={cs.CL},
       url={https://arxiv.org/abs/2506.08672}, 
 }
-```
+```
+
+Code: https://github.com/bigai-nlco/RuleReasoner