This PR updates the dataset card of `ConnectomeBench2` to:
- Link the dataset to its corresponding paper: [ConnectomeBench2: A Unified Benchmark for Automated Connectomic Proofreading](https://huggingface.co/papers/2606.21116)
- Provide a link to the official GitHub repository: https://github.com/timfarkas/ConnectomeBench2
- Set the `task_categories` metadata to `image-classification`