updates changelog for 6.1.6

CHANGELOG.md

 # 6.2.0 (unreleased)
 
+# 6.1.6 (2019-04-29)
+### Features / Enhancements
+* **Security**: Bump jQuery to 3.4.0 . [#16761](https://github.com/grafana/grafana/pull/16761), [@dprokop](https://github.com/dprokop)
+
+### Bug Fixes
+* **Playlist**: Fix loading dashboards by tag. [#16727](https://github.com/grafana/grafana/pull/16727), [@marefr](https://github.com/marefr)
+
+# 6.1.5 (2019-04-29)
+
+* **Security**: Urgent security patch release. Please read more in our [blog](https://grafana.com/blog/2019/04/29/grafana-5.4.4-and-6.1.6-released-with-important-security-fix/)
+
 # 6.1.4 (2019-04-16)
 
 ### Bug Fixes

latest.json

 {
-  "stable": "6.1.3",
-  "testing": "6.1.3"
+  "stable": "6.1.6",
+  "testing": "6.1.6"
 }