Update changelog

Author: tmattio

CHANGES.md

@@ -97,6 +97,7 @@ All notable changes to this project will be documented in this file.
 
 ### Fehu
 
+- Added snapshot-based save/load for DQN and REINFORCE agents (#127, @RidwanAdebosin, @tmattio)
 - Added typed `Render` payloads with enforced `render_mode` selection in `Env.create`, auto human-mode rendering, and vectorized `Env.render` accessors so environments consistently expose frames for downstream tooling (@tmattio)
 - Introduced the `Fehu_visualize` library with ffmpeg/gif/W&B sinks, overlay combinators, rollout/evaluation recorders, and video wrappers for single and vectorized environments, providing a cohesive visualization stack for Fehu (@tmattio)
 - Reworked space sampling to return `(value, next_rng)` and split keys internally, fixing correlated draws in Box/Multi-discrete/Tuple/Dict/Sequence/Text samplers while adding `Space.boundary_values` for deterministic compatibility checks (@tmattio)
@@ -178,11 +179,6 @@ We've expanded Kaun with high-level APIs for deep learning. These APIs are inspi
 - Model zoo: Reference implementations of classic and modern architectures (LeNet5 for basic CNNs, BERT for masked language modeling, GPT2 for autoregressive generation) including reusable transformer components
 - Ecosystem integration: Load HuggingFace model architectures (`kaun.huggingface`), access common datasets like MNIST and CIFAR-10 (`kaun.datasets`), and use standardized model definitions (`kaun.models`)
 
-## [Unreleased]
-### Added
-- Implemented save/load serialization for Fehu's DQN agent.
-- Added regression tests to verify agent outputs after save/load.
-
 ### Contributors
 
 Thanks to everyone who contributed to this release: