docs: add changelog entry for PR 1455

Author: brendan-kellam

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- Added an opt-in `SOURCEBOT_LLM_USER_EMAIL_HEADER_ENABLED` environment variable that sends the authenticated user's lower-cased email to language model providers in the `X-Sourcebot-User-Email` header. [#1455](https://github.com/sourcebot-dev/sourcebot/pull/1455)
+
 ### Fixed
 - [EE] Verified signed online license assertions before granting paid feature entitlements. [#1442](https://github.com/sourcebot-dev/sourcebot/pull/1442)
 - [EE] Fixed worker startup races that could disable GitHub App authentication and permission syncing until restart after an online license refresh. [#1454](https://github.com/sourcebot-dev/sourcebot/pull/1454)