Update ChangeLog

Author: tshu-w

src/lightning/pytorch/CHANGELOG.md

@@ -35,6 +35,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed `_LoggerConnector`'s `_ResultMetric` to move all registered keys to the device of the logged value if needed ([#19814](https://github.com/Lightning-AI/pytorch-lightning/issues/19814))
 - Fixed `_optimizer_to_device` logic for special 'step' key in optimizer state causing performance regression ([#20019](https://github.com/Lightning-AI/lightning/pull/20019))
 - Fixed parameter counts in `ModelSummary` when model has distributed parameters (DTensor) ([#20163](https://github.com/Lightning-AI/pytorch-lightning/pull/20163))
+- Fixed PyTorch Lightning FSDP takes more memory than PyTorch FSDP ([#20323](https://github.com/Lightning-AI/pytorch-lightning/pull/20323))
 
 
 ## [2.3.0] - 2024-06-13