Add GAP dataset
This dataset already exists apparently, sorry :/ 
see
https://github.com/huggingface/datasets/blob/master/datasets/gap/gap.py

Feel free to re-use the dataset card you did for `/datasets/gap`
 oh heck, my bad 🤦‍♂️ sorry I think you should also delete this branch.
GAP dataset
Gender bias coreference resolution