Add source info of GitTables

Hi,

Thanks for your effort to host the GitTables dataset on HuggingFace!
I've added information about the source to help users understand the dataset better.

Kind regards,
Madelon Hulsebos

README.md

@@ -1,3 +1,19 @@
 ---
 license: cc-by-nc-nd-3.0
 ---
+
+## More information and source of GitTables:
+- Website: https://gittables.github.io/
+- Paper: https://dl.acm.org/doi/pdf/10.1145/3588710
+- Dataset page: https://zenodo.org/records/6517052
+- Citation format:
+@article{hulsebos2023gittables,
+  title={Gittables: A large-scale corpus of relational tables},
+  author={Hulsebos, Madelon and Demiralp, {\c{C}}agatay and Groth, Paul},
+  journal={Proceedings of the ACM on Management of Data},
+  volume={1},
+  number={1},
+  pages={1--17},
+  year={2023},
+  publisher={ACM New York, NY, USA}
+}