Added 4.0.0-alpha2 tag and headings for next release

Author: Sam Tuke

CHANGELOG.md

@@ -4,7 +4,19 @@ All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](https://semver.org/).
 
 
-## x.y.z
+## x.y.z (next release)
+
+### Added
+
+### Changed
+
+### Deprecated
+
+### Removed
+
+### Fixed
+
+## 4.0.0-alpha2
 
 ### Added
 - Integration tests for the dev and test environment (#44)