Update changelog for 5.7.1

Author: eleanorakh

CHANGELOG.md

@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [v5.7.1](https://github.com/buildkite/elastic-ci-stack-for-aws/compare/v5.7.0...v5.7.1) (2021-10-14)
+
+### Added
+
+* Add new docs links to template file
+
 ## [v5.7.0](https://github.com/buildkite/elastic-ci-stack-for-aws/compare/v5.6.1...v5.7.0) (2021-09-29)
 
 ### Added