Add CHANGELOG entry for PR #889

Co-authored-by: Gui-FernandesBR <63590233+Gui-FernandesBR@users.noreply.github.com>

Author: Copilot

CHANGELOG.md

@@ -45,6 +45,7 @@ Attention: The newest changes should be on top -->
 
 ### Fixed
 
+- BUG: Fix hard-coded radius value for parachute added mass calculation [#889](https://github.com/RocketPy-Team/RocketPy/pull/889)
 - BUG: Fix parallel Monte Carlo simulation showing incorrect iteration count [#806](https://github.com/RocketPy-Team/RocketPy/pull/806)
 - BUG: Fix CSV column header spacing in FlightDataExporter [#864](https://github.com/RocketPy-Team/RocketPy/issues/864)