prepare changelog for release (from GitHub Actions)

Author: CCDL-Bot

CHANGELOG.md

@@ -4,6 +4,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
+## [2.1.0] 2026-03-20
 ### Changed
 - Changed scaling behaviour for json widget. Depending on content, it scales to 1-5 rows initially. When the user pastes multi-line json it also rescales to fit the content. [#344](https://github.com/CCDirectLink/crosscode-map-editor/issues/344)