test2 (update citations)

PiperOrigin-RevId: 633688212

README.md

@@ -5,6 +5,7 @@
 * [Discovering Adaptable Symbolic Algorithms from Scratch](https://arxiv.org/abs/2307.16890) (IROS 2023, Best Paper Finalist)
 * [Visual-Locomotion: Learning to Walk on Complex Terrains with Vision](https://proceedings.mlr.press/v164/yu22a.html) (CoRL 2022)
 * [ES-ENAS: Efficient Evolutionary Optimization for Large Hybrid Search Spaces](https://arxiv.org/abs/2101.07415) (arXiv, 2021)
+* [Hierarchical Reinforcement Learning for Quadruped Locomotion](https://arxiv.org/abs/1905.08926) (RSS 2021)
 * [Rapidly Adaptable Legged Robots via Evolutionary Meta-Learning](https://arxiv.org/abs/2003.01239) (IROS 2020)
 * [Robotic Table Tennis with Model-Free Reinforcement Learning](https://arxiv.org/abs/2003.14398) (IROS 2020)
 * [ES-MAML: Simple Hessian-Free Meta Learning](https://arxiv.org/abs/1910.01215) (ICLR 2020)