message: updating bark citation
diff: @@ -54,13 +54,12 @@ For a more detailed understanding of how BARK works, its concept and use cases h
  If you use BARK, please cite us using the following paper:
  ```
  -@misc{bernhard2020bark,
  +@inproceedings{Bernhard2020,
  title = {BARK: Open Behavior Benchmarking in Multi-Agent Environments},
  - author={Julian Bernhard and Klemens Esterle and Patrick Hart and Tobias Kessler},
  - year={2020},
  - eprint={2003.02604},
  - archivePrefix={arXiv},
  - primaryClass={cs.MA}
  + author = {Bernhard, Julian and Esterle, Klemens and Hart, Patrick and Kessler, Tobias},
  + booktitle = {2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)},
  + url = {https://arxiv.org/pdf/2003.02604.pdf},
  + year = {2020}
  }
  ```
  