update changelog

Author: korbireischl

CHANGELOG.md

@@ -10,12 +10,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 * Added instructions for fixing problems on Windows.
-* Added function to set additional vertical loads.
+* Added gravity variable and function to set additional vertical loads.
 
 ### Changed
 
-* The force calculation now works in SI-units.
-
 ### Removed