Add OffensEval-TR 2020 Dataset
@lhoestq, can you please review this PR?  > Awesome thank you !

Thanks for the small fixes @lhoestq  @coltekin, we have added the data set that you created an article that says "Turkish Attack Language Community in Social Media", HuggingFace dataset update sprint for you. We added Sprint quickly for a short time. I hope you welcome it too. The dataset is accessible at https://huggingface.co/datasets/offenseval2020_tr.  Thank you for the heads up. I am not familiar with the terminology above (no idea what a sprint is), but I am happy that you found the data useful. Please feel free to distribute/use it as you see fit.

The OffensEval version you included in your data set has only binary labels. There is also a version [here](https://coltekin.github.io/offensive-turkish/troff-v1.0.tsv.gz) which also includes fine-grained labels similar to the OffensEval English data set - Just in case it would be of interest.

If you have questions about the data set, or need more information please let me know.
This PR adds the OffensEval-TR 2020 dataset which is a Turkish offensive language corpus by me and @basakbuluz. The corpus consist of randomly sampled tweets and annotated in a similar way to [OffensEval](https://sites.google.com/site/offensevalsharedtask/) and [GermEval](https://projects.fzai.h-da.de/iggsa/).

- **Homepage:** [offensive-turkish](https://coltekin.github.io/offensive-turkish/)
- **Paper:** [A Corpus of Turkish Offensive Language on Social Media](https://coltekin.github.io/offensive-turkish/troff.pdf)
- **Point of Contact:** [Çağrı Çöltekin](ccoltekin@sfs.uni-tuebingen.de)