Add dataset card, link to paper

This PR ensures the dataset is linked to (and can be found at) https://huggingface.co/papers/2503.21776.
It also adds a link to the Github repository and the appropriate task category.

README.md

@@ -1,3 +1,9 @@
----
-license: apache-2.0
----
+---
+license: apache-2.0
+task_categories:
+- video-question-answering
+---
+
+This repository contains the data presented in [Video-R1: Reinforcing Video Reasoning in MLLMs](https://huggingface.co/papers/2503.21776).
+
+Code: https://github.com/tulerfeng/Video-R1