Update release notes for version 2.1.0

Author: timo282

docs/release-notes/v2.1.0.md

@@ -1,4 +1,4 @@
-## Release vX.X.X
+## Release v2.1.0
 ### What's changed
 
 #### Added features:
@@ -17,4 +17,4 @@
 * core functionalities of classification task has been moved to base task to prevent code duplication for other tasks
 * test coverage is now boosted to >90%
 
-**Full Changelog**: [here](https://github.com/finitearth/promptolution/compare/W.W.W...vX.X.X)
+**Full Changelog**: [here](https://github.com/finitearth/promptolution/compare/2.0.1...v2.1.0)