This PR improves the dataset card for the `MuMo-Pretraining` dataset by:
- Adding the `graph-ml` task category to the metadata.
- Adding a link to the GitHub repository (`https://github.com/selmiss/MuMo`).
- Replacing the truncated abstract with the full abstract from the paper.
- Adding descriptive tags (`chemistry`, `molecular-biology`, `drug-discovery`, `multi-modal`).
