Update changelog.md

changelog.md

 # Changelog
 
 All notable changes to this project will be documented in this file.
+
+## [0.4] - 2021-03-03
+- Provisioning is now limited to a single org at once.
+
 ## [0.3] - 2021-03-03
 - Tune down the amount of concurrency, as Grafana servers can't keep up