Add a publication into the list (#129)

README.md

@@ -29,6 +29,7 @@ Please use this bibtex if you want to cite this repository in your publications:
 ```
 
 List of publications & submissions using MiniGrid or BabyAI (please open a pull request to add missing entries):
+- [BeBold: Exploration Beyond the Boundary of Explored Regions](https://arxiv.org/pdf/2012.08621.pdf) (UCB, December 2020)
 - [Approximate Information State for Approximate Planning and Reinforcement Learning in Partially Observed Systems](https://arxiv.org/abs/2010.08843) (McGill, October 2020)
 - [Prioritized Level Replay](https://arxiv.org/pdf/2010.03934.pdf) (FAIR, October 2020)
 - [AllenAct: A Framework for Embodied AI Research](https://arxiv.org/pdf/2008.12760.pdf) (Allen Institute for AI, August 2020)