chore: update CHANGELOG for #989

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: brendan-kellam

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 - [EE] Added multi-owner support with promote/demote actions. [#988](https://github.com/sourcebot-dev/sourcebot/pull/988)
+- [EE] Added `PERMISSION_SYNC_USER_DRIVEN_ENABLED` and `PERMISSION_SYNC_REPO_DRIVEN_ENABLED` environment variables to independently enable/disable user-driven and repo-driven permission syncing. [#989](https://github.com/sourcebot-dev/sourcebot/pull/989)
 
 ## [4.15.3] - 2026-03-10