Add LeanRL as a related project (#484)

* Update README.md

* Update README.md

README.md

@@ -28,7 +28,11 @@ CleanRL is a Deep Reinforcement Learning library that provides high-quality sing
 
 You can read more about CleanRL in our [JMLR paper](https://www.jmlr.org/papers/volume23/21-1342/21-1342.pdf) and [documentation](https://docs.cleanrl.dev/).
 
-CleanRL only contains implementations of **online** deep reinforcement learning algorithms. If you are looking for **offline** algorithms, please check out [corl-team/CORL](https://github.com/corl-team/CORL), which shares a similar design philosophy as CleanRL.
+Notable CleanRL-related projects:
+
+* [corl-team/CORL](https://github.com/corl-team/CORL): Offline RL algorithm implemented in CleanRL style
+* [pytorch-labs/LeanRL](https://github.com/pytorch-labs/LeanRL): Fast optimized PyTorch implementation of CleanRL RL algorithms using CUDAGraphs.
+
 
 > ℹ️ **Support for Gymnasium**: [Farama-Foundation/Gymnasium](https://github.com/Farama-Foundation/Gymnasium) is the next generation of [`openai/gym`](https://github.com/openai/gym) that will continue to be maintained and introduce new features. Please see their [announcement](https://farama.org/Announcing-The-Farama-Foundation) for further detail. We are migrating to `gymnasium` and the progress can be tracked in [vwxyzjn/cleanrl#277](https://github.com/vwxyzjn/cleanrl/pull/277).