Update release notes

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

RELEASE_NOTES.md

@@ -15,6 +15,8 @@
    actor = ConfigManagingActor(config_files=["config.toml"])
    ```
 
+* The `ComponentMetricsRequest` now produces a channel name without the `start_date` if the `start_date` is `None`. If you are somehow relying on the old behavior, please update your code.
+
 ## New Features
 
 - The `ConfigManagingActor` can now take multiple configuration files as input, allowing to override default configurations with custom configurations.