Update CHANGELOG.md

CHANGELOG.md

@@ -14,6 +14,7 @@
 * **Prometheus**: Adhoc-filtering for Prometheus dashboards [#13212](https://github.com/grafana/grafana/issues/13212)
 * **Singlestat**: Fix gauge display accuracy for percents [#13270](https://github.com/grafana/grafana/issues/13270), thx [@tianon](https://github.com/tianon)
 * **Dashboard**: Prevent auto refresh from starting when loading dashboard with absolute time range [#12030](https://github.com/grafana/grafana/issues/12030)
+* **Templating**: New templating variable type `Text box` that allows free text input [#3173](https://github.com/grafana/grafana/issues/3173)
 
 # 5.3.0 (unreleased)