Feat: Add Acknowledgements

Author: choru-k

README.md

@@ -53,4 +53,10 @@ So you can run this example in your computer(maybe it take just only 1~2 minitue
 [16][RECURRENT EXPERIENCE REPLAY IN DISTRIBUTED REINFORCEMENT LEARNING](https://openreview.net/pdf?id=r1lyTjAqYX)  
 [17][EXPLORATION BY RANDOM NETWORK DISTILLATION](https://openreview.net/pdf?id=H1lJJnR5Ym)  
 [18][Distributional Reinforcement Learning with Quantile Regression](https://arxiv.org/pdf/1710.10044.pdf)  
-[19][Implicit Quantile Networks for Distributional Reinforcement Learning](https://arxiv.org/pdf/1806.06923.pdf)  
+[19][Implicit Quantile Networks for Distributional Reinforcement Learning](https://arxiv.org/pdf/1806.06923.pdf)  
+
+## Acknowledgements
+- https://github.com/openai/baselines
+- https://github.com/reinforcement-learning-kr/pg_travel
+- https://github.com/reinforcement-learning-kr/distributional_rl
+- https://github.com/Kaixhin/Rainbow