Add pipeline tag and ensure correct license information

This PR adds the `pipeline_tag: text-ranking` to improve the model's discoverability on the Hugging Face Hub. The license information has also been slightly corrected for clarity. The existing links to the Github repository and paper are retained.

README.md

@@ -1,8 +1,9 @@
 ---
-library_name: transformers
-license: mit
 base_model:
 - google/gemma-2-2b-it
+library_name: transformers
+license: mit
+pipeline_tag: text-ranking
 ---
 
 # R<sup>2</sup>ec: Towards Large Recommender Models with Reasoning
@@ -10,8 +11,6 @@ base_model:
 R<sup>2</sup>ec is a large recommender model with reasoning, generating both natural language rationales and ranked item predictions. 
 The model is fine-tuned with reinforcement learning to enhance its reasoning capabilities for more effective recommendations.
 
- 
-
 <p align="center">
   <a href="https://arxiv.org/pdf/2505.16994"><b>Paper Link</b>👁️</a>
 </p>
@@ -23,8 +22,8 @@ The model is fine-tuned with reinforcement learning to enhance its reasoning cap
 - **Paper:** https://arxiv.org/abs/2505.16994
 
 ## Licence
-This code repository is licensed under MIT License. 
-The use of R<sup>2</sup>ec models is also subject to MIT License. 
+This code repository is licensed under the MIT License. 
+The use of R<sup>2</sup>ec models is also subject to the MIT License. 
 R<sup>2</sup>ec series support commercial use and distillation.
 
 ## Citation