changelog: notes about closing #11498

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CHANGELOG.md

+# 5.2.0 (unreleased)
+
+### Minor
+
+* **Graph**: Show invisible highest value bucket in histogram [#11498](https://github.com/grafana/grafana/issues/11498)
+
+
 # 5.1.0 (2018-04-26)
 
 * **Folders**: Default permissions on folder are not shown as inherited in its dashboards [#11668](https://github.com/grafana/grafana/issues/11668)