Add gitlab managed apps section to dev docs

doc/development/kubernetes.md

@@ -123,3 +123,10 @@ they are written:
 ```bash
 kubectl logs <pod_name> --follow -n gitlab-managed-apps
 ```
+
+## GitLab Managed Apps
+
+GitLab provides [GitLab Managed Apps](../user/clusters/applications.html), a one-click install for various applications which can be added directly to your configured cluster.
+
+**<i class="fa fa-youtube-play youtube" aria-hidden="true"></i>
+For an overview of how to add a new GitLab-mananged app, see [How to add GitLab-managed-apps to Kubernetes integration](https://youtu.be/mKm-jkranEk).**