Update README.md

[Original Homepage](https://developer.ibm.com/exchanges/data/all/pubtabnet/)



@article
{zhong2019pubtabnet,
title={Image-based table recognition: data, model, and evaluation},
author={Xu Zhong and Elaheh ShafieiBavani and Antonio Jimeno Yepes},
journal={arXiv preprint arXiv:1911.10683},
year={2019}
}

README.md

@@ -27,4 +27,11 @@ configs:
     path: data/train-*
   - split: validation
     path: data/validation-*
----
+license: cdla-permissive-1.0
+task_categories:
+- visual-question-answering
+- image-to-text
+- text-generation
+size_categories:
+- 100K<n<1M
+---