docs: update CHANGELOG.md

Co-authored-by: Jakob Schnell <[email protected]>

Author: merydian

CHANGELOG.md

@@ -40,7 +40,7 @@ RELEASING:
 14. Create new release in GitHub with tag version and release title of `vX.X.X`
  -->
 
-# Unreleased
+## Unreleased
 - Make vertex marker on map drag and droppable, add live preview ([#204](https://github.com/GIScience/orstools-qgis-plugin/issues/204))
 
 ## [1.9.0] - 2024-10-29