changelog: adds #7554 - minor enhancement to 4.2.0

CHANGELOG.md

@@ -23,6 +23,7 @@
 * **Datasources** Delete datsource by name [#7476](https://github.com/grafana/grafana/issues/7476), thx [@huydx](https://github.com/huydx)
 * **Dataproxy**: Only allow get that begins with api/ to access Prometheus [#7459](https://github.com/grafana/grafana/pull/7459), thx [@mtanda](https://github.com/mtanda)
 * **Snapshot**: Make timeout for snapshot creation configurable [#7449](https://github.com/grafana/grafana/pull/7449) thx [@ryu1-sakai](https://github.com/ryu1-sakai)
+* **Panels**: Add more physics units [#7554](https://github.com/grafana/grafana/pull/7554) thx [@ryantxu](https://github.com/ryantxu)
 
 ## Tech