Update CHANGELOG.md

CHANGELOG.md

@@ -14,6 +14,7 @@
 * **Prometheus**: Adds /metrics endpoint for exposing Grafana metrics. [#9187](https://github.com/grafana/grafana/pull/9187)
 * **Graph**: Add support for local formating in axis. [#1395](https://github.com/grafana/grafana/issues/1395), thx [@m0nhawk](https://github.com/m0nhawk)
 * **Jaeger**: Add support for open tracing using jaeger in Grafana. [#9213](https://github.com/grafana/grafana/pull/9213)
+* **Unit types**: New date & time unit types added, useful in singlestat to show dates & times. [#3678](https://github.com/grafana/grafana/issues/3678), [#6710](https://github.com/grafana/grafana/issues/6710), [#2764](https://github.com/grafana/grafana/issues/6710)
 
 ## Breaking changes
 * **Metrics**: The metric structure for internal metrics about Grafana published to graphite has changed. This might break dashboards for internal metrics.