Add changelog for v5.3.3

Author: keithduncan

CHANGELOG.md

@@ -4,6 +4,22 @@ 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).
 
+## [v5.3.3](https://github.com/buildkite/elastic-ci-stack-for-aws/compare/v5.3.2...v5.3.3) (2021-06-30)
+
+### Added
+
+* Docker Buildx [#871](https://github.com/buildkite/elastic-ci-stack-for-aws/pull/871)
+* Docs on which user SSH access applies to [#863](https://github.com/buildkite/elastic-ci-stack-for-aws/pull/863) ([@Temikus](https://github.com/Temikus))
+
+### Changed
+
+* Update Buildkite Agent to version 3.30.0 [#868](https://github.com/buildkite/elastic-ci-stack-for-aws/pull/868) ([@esalter](https://github.com/esalter))
+* The HttpPutResponseHopLimit from 1 to 2 [#858](https://github.com/buildkite/elastic-ci-stack-for-aws/pull/858)
+
+### Fixed
+
+* The default cost allocation tag value [#859](https://github.com/buildkite/elastic-ci-stack-for-aws/pull/859)
+
 ## [v5.3.2](https://github.com/buildkite/elastic-ci-stack-for-aws/compare/v5.3.1...v5.3.2) (2021-06-11)
 
 ### Fixed