Fix PPO blog post link recurrentppo (#330)

* Fixed dead link.

* Updated changelog.

---------

Co-authored-by: Cemal Yilmaz <Cemal.Yilmaz@telematik-zentrum.de>

Author: Tanki777

README.md

@@ -28,7 +28,7 @@ See documentation for the full list of included features.
 - [Augmented Random Search (ARS)](https://arxiv.org/abs/1803.07055)
 - [Quantile Regression DQN (QR-DQN)](https://arxiv.org/abs/1710.10044)
 - [PPO with invalid action masking (MaskablePPO)](https://arxiv.org/abs/2006.14171)
-- [PPO with recurrent policy (RecurrentPPO aka PPO LSTM)](https://ppo-details.cleanrl.dev//2021/11/05/ppo-implementation-details/)
+- [PPO with recurrent policy (RecurrentPPO aka PPO LSTM)](https://iclr-blog-track.github.io/2022/03/25/ppo-implementation-details/)
 - [Truncated Quantile Critics (TQC)](https://arxiv.org/abs/2005.04269)
 - [Trust Region Policy Optimization (TRPO)](https://arxiv.org/abs/1502.05477)
 - [Batch Normalization in Deep Reinforcement Learning (CrossQ)](https://openreview.net/forum?id=PczQtTsTIX)

docs/misc/changelog.md

@@ -2,6 +2,22 @@
 
 # Changelog
 
+## Release 2.8.1a0 (WIP)
+
+### Breaking Changes:
+
+### New Features:
+
+### Bug Fixes:
+
+### Deprecations:
+
+### Others:
+
+### Documentation:
+- Fixed dead link for `RecurrentPPO`.
+
+
 ## Release 2.8.0 (2026-04-01)
 
 ### Breaking Changes: