added BibTex entry and citation info

README.md

@@ -27,3 +27,16 @@ learning_rate = 3e-4
 adam_epsilon = 1e-8
 train_batch_size = 6
 ``` 
+
+### BibTeX entry and citation info
+
+```bibtex
+@misc{shrivastava2020saying,
+      title={Saying No is An Art: Contextualized Fallback Responses for Unanswerable Dialogue Queries}, 
+      author={Ashish Shrivastava and Kaustubh Dhole and Abhinav Bhatt and Sharvani Raghunath},
+      year={2020},
+      eprint={2012.01873},
+      archivePrefix={arXiv},
+      primaryClass={cs.CL}
+}
+```