Merge pull request #4555 from oleibman/breakdoc

Changelog Update Semantic Versioning Statement

Author: oleibman

CHANGELOG.md

@@ -3,7 +3,7 @@
 All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com)
-and this project adheres to [Semantic Versioning](https://semver.org).
+and this project adheres to [Semantic Versioning](https://semver.org). Thia is always true of the master branch. Some earlier branches remain supported and security fixes are applied to them; if the security fix represents a breaking change, it may have to be applied as a minor or patch version.
 
 ## TBD - 5.0.0