add changelog

Author: tchaton

CHANGELOG.md

@@ -279,6 +279,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Updated error message for interactive incompatible plugins ([#9896](https://github.com/PyTorchLightning/pytorch-lightning/pull/9896))
 
 
+- Changed `training_type_plugin` in favor of `accelerator` within the loops ([#9901](https://github.com/PyTorchLightning/pytorch-lightning/pull/9901))
+
+
 ### Deprecated
 
 - Deprecated trainer argument `terminate_on_nan` in favour of `detect_anomaly`([#9175](https://github.com/PyTorchLightning/pytorch-lightning/pull/9175))