docs: update CHANGELOG for v2.0.0 release

CHANGELOG.md

@@ -2,6 +2,19 @@
 
 All notable changes to this Cloudron package will be documented in this file.
 
+## [2.0.0] - 2025-10-22
+
+### Updated
+- Updated mautrix-whatsapp to v0.2510.0 (latest release as of October 2025)
+- Major version bump due to upstream versioning scheme change (from v0.12.x to v0.2510.0)
+
+### Fixed
+- Improved registration file regex pattern from `.*` to `.+` for better user matching
+
+### Changes in v0.2510.0
+- This release includes all improvements and fixes from upstream mautrix-whatsapp v0.2510.0
+- See https://github.com/mautrix/whatsapp/releases/tag/v0.2510.0 for detailed upstream changes
+
 ## [1.2.2] - 2025-08-22
 
 ### Updated