Improve model card (pipeline tag, add Github link)

This PR improves the model card by changing the pipeline tag to `text-generation` to improve discoverability. It also adds a link to the Github repository for the project.

README.md

@@ -1,13 +1,13 @@
 ---
-license: mit
+base_model:
+- Qwen/Qwen3-8B-Base
 datasets:
 - RuleReasoner/rule-reasoning
 language:
 - en
-base_model:
-- Qwen/Qwen3-8B-Base
-pipeline_tag: question-answering
 library_name: transformers
+license: mit
+pipeline_tag: text-generation
 tags:
 - rule-based reasoning
 ---
@@ -25,4 +25,6 @@ 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