Changed: Add diameter to CHANGELOG

Author: kayjan

CHANGELOG.md

@@ -6,6 +6,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Added
+- BaseNode: Add diameter property.
 - Misc: Testing to include benchmark timings for tree creation, compare benchmark tests across commits, reject pull request if benchmark tests fails.
 - Misc: Documentation to include benchmark results.
 ### Changed