Fix link to Hugging Face Hub in OpenEnv documentation (#5229)

Co-authored-by: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>

Author: thesteve0

docs/source/openenv.md

@@ -1,6 +1,6 @@
 # OpenEnv Integration for Training LLMs with Environments
 
-[OpenEnv](https://github.com/meta-pytorch/OpenEnv) is an open-source framework from Meta's PyTorch team for defining, deploying, and interacting with environments in reinforcement learning (RL) and agentic workflows. It offers [Gymnasium-style APIs](https://gymnasium.farama.org) (e.g., `reset()` and `step()`) to interface with environments in a standard manner, and supports running these environments as backend servers (for example, via HTTP or containerised execution). You can find a collection of ready-to-use OpenEnv environments on the [Hugging Face Hub](https://huggingface.co/collections/openenv/environment-hub).
+[OpenEnv](https://github.com/meta-pytorch/OpenEnv) is an open-source framework from Meta's PyTorch team for defining, deploying, and interacting with environments in reinforcement learning (RL) and agentic workflows. It offers [Gymnasium-style APIs](https://gymnasium.farama.org) (e.g., `reset()` and `step()`) to interface with environments in a standard manner, and supports running these environments as backend servers (for example, via HTTP or containerised execution). You can find a collection of ready-to-use OpenEnv environments on the [Hugging Face Hub](https://huggingface.co/collections/openenv/openenv-environment-hub).
 
 In this guide, we’ll focus on **how to integrate OpenEnv with TRL**, but feel free to explore the links above to dive deeper into OpenEnv itself.