fix broken URL to paper

README.md

@@ -31,7 +31,7 @@ This is the model card of a 🤗 transformers model that has been pushed on the
 <!-- Provide the basic links for the model. -->
 
 - **Repository:** [More Information Needed]
-- **Paper [STILL-2]:** [https://arxiv.org/abs/2412.09413]
+- **Paper [STILL-2]:** https://arxiv.org/abs/2412.09413
 - **Demo [optional]:** [More Information Needed]
 
 ## Uses