Add add cc-by-sa-2.5 license tag
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_4818). All of your documentation changes will be reflected on that endpoint. I think we can close this PR because the `standard_licenses.tsv` file was removed from this repo and we no longer perform any dataset card validation.
- [ ] add it to moon-landing
- [ ] add it to hub-docs 