Release: Updates Changelog for 6.5.1 (#20723)

* Release: Changes for 6.5.1

* Add issue to 6.5.1 release

* Changed PR title

CHANGELOG.md

 # 6.6.0 (unreleased)
 
+# 6.5.1 (2019-11-28)
+
+### Bug Fixes
+* **CloudWatch**: Region template query fix. [#20661](https://github.com/grafana/grafana/pull/20661), [@sunker](https://github.com/sunker)
+* **CloudWatch**: Fix annotations query editor loading. [#20687](https://github.com/grafana/grafana/pull/20687), [@sunker](https://github.com/sunker)
+* **Panel**: Fixes undefined services/dependencies in plugins without `/**@ngInject*/`. [#20696](https://github.com/grafana/grafana/pull/20696), [@hugohaggmark](https://github.com/hugohaggmark)
+* **Server**: Fix failure to start with "bind: address already in use" when using socket as protocol. [#20679](https://github.com/grafana/grafana/pull/20679), [@aknuds1](https://github.com/aknuds1)
+* **Stats**: Fix active admins/editors/viewers stats are counted more than once if the user is part of more than one org. [#20711](https://github.com/grafana/grafana/pull/20711), [@papagian](https://github.com/papagian)
+
 # 6.5.0 (2019-11-25)
 
 ### Features / Enhancements