Release: updated changelog with v6.2 entries (#17201)

* Release: updated changelog with v6.2 entries

* Release: Updated changelog

CHANGELOG.md

-# 6.2.0 (unreleased)
+# 6.2.0 (2019-05-22)
+
+### Bug Fixes
+* **BarGauge**: Fix for negative min values. [#17192](https://github.com/grafana/grafana/pull/17192), [@torkelo](https://github.com/torkelo)
+* **Gauge/BarGauge**: Fix for issues editing min & max options. [#17174](https://github.com/grafana/grafana/pull/17174)
+
+### Breaking Changes
+* **Plugins**: Data source plugins that process hidden queries need to add a "hiddenQueries: true" attribute in plugin.json. [#17124](https://github.com/grafana/grafana/pull/17124), [@ryantxu](https://github.com/ryantxu)
+
+### Removal of old deprecated package repository
+
+5 months ago we deprecated our old package cloud repository and [replaced it](https://grafana.com/blog/2019/01/05/moving-to-packages.grafana.com/) with our own. We will remove the old depreciated
+repo on July 1st. Make sure you have switched to the new repo by then. The new repository has all our old releases so you are not required to upgrade just to switch package repository.
 
 # 6.2.0-beta2 (2019-05-15)