Update CHANGELOG with recent fixes

Added a note about fixing zoekt indexing issue with pipe in branch/tag names.

Author: xPartyBear

CHANGELOG.md

@@ -6,6 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+- Fixed zoekt indexing failing with pipe in branch/tag names [#506](https://github.com/sourcebot-dev/sourcebot/pull/506)
 
 ## [4.6.8] - 2025-09-15