changelog: update for v5.1.0

CHANGELOG.md

@@ -1,3 +1,11 @@
+# 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)
+* **Templating**: Allow more than 20 previews when creating a variable [#11508](https://github.com/grafana/grafana/issues/11508)
+* **Dashboard**: Row edit icon not shown [#11466](https://github.com/grafana/grafana/issues/11466)
+* **SQL**: Unsupported data types for value column using time series query [#11703](https://github.com/grafana/grafana/issues/11703)
+* **Prometheus**: Prometheus query inspector expands to be very large on autocomplete queries [#11673](https://github.com/grafana/grafana/issues/11673)
+
 # 5.1.0-beta1 (2018-04-20)
 
 * **MSSQL**: New Microsoft SQL Server data source [#10093](https://github.com/grafana/grafana/pull/10093), [#11298](https://github.com/grafana/grafana/pull/11298), thx [@linuxchips](https://github.com/linuxchips)