Update changelog.md

changelog.md

 # Changelog
 
 All notable changes to this project will be documented in this file.
+## [0.3] - 2021-03-03
+- Tune down the amount of concurrency, as Grafana servers can't keep up
 
 ## [0.2] - 2021-03-03
 - Generate and provision dashboards concurrently to reduce time to provision