CHANGELOG.md: add lines for #2083

Author: joelanford

CHANGELOG.md

@@ -6,6 +6,11 @@
 
 ### Changed
 
+- Upgrade Kubernetes version from `kubernetes-1.14.1` to `kubernetes-1.15.4`. ([#2083](https://github.com/operator-framework/operator-sdk/pull/2083))
+- Upgrade Helm version from `v2.14.1` to `v2.15.0`. ([#2083](https://github.com/operator-framework/operator-sdk/pull/2083))
+- Upgrade [`controller-runtime`](https://github.com/kubernetes-sigs/controller-runtime) version from `v0.2.0` to `v0.3.0`. ([#2083](https://github.com/operator-framework/operator-sdk/pull/2083))
+- Upgrade [`controller-tools`](https://github.com/kubernetes-sigs/controller-tools) version from `v0.2.1+git` to `v0.2.2`. ([#2083](https://github.com/operator-framework/operator-sdk/pull/2083))
+
 ### Deprecated
 
 ### Removed