Add model card

This PR:
- ensures the model is linked to (and shows up at) https://huggingface.co/papers/2504.20571
- has a linked base model (Qwen/Qwen2.5-Math-7B)
- has a "Use this model" button at the top right, by adding the `library_name` metadata.

README.md

@@ -1,3 +1,11 @@
----
-license: apache-2.0
----
+---
+license: apache-2.0
+library_name: transformers
+pipeline_tag: text-generation
+base_model:
+- Qwen/Qwen2.5-Math-7B
+---
+
+This repository contains the model presented in [Reinforcement Learning for Reasoning in Large Language Models with One Training Example](https://huggingface.co/papers/2504.20571).
+
+Code: https://github.com/ypwang61/One-Shot-RLVR