Add changelog entry

Author: gilles-gosuin

charts/external-dns/CHANGELOG.md

@@ -20,6 +20,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [UNRELEASED]
 
+### Added
+
+- Added the option to explicitly enable or disable service account token automounting. ([#3983](https://github.com/kubernetes-sigs/external-dns/pull/3983)) [@gilles-gosuin](https://github.com/gilles-gosuin)
+
 ## [v1.13.1] - 2023-09-07
 
 ### Added