README: add certified kubernetes badge
@@ -10,6 +10,8 @@ not shipped with upstream Kubernetes.
## Features
+<a href="https://landscape.cncf.io/selected=lokomotive"><img src="https://raw.githubusercontent.com/cncf/artwork/1c1a10d9cc7de24235e07c8831923874331ef233/projects/kubernetes/certified-kubernetes/versionless/color/certified-kubernetes-color.svg" align="right" width="100px"></a>
+
* Kubernetes 1.18 (upstream, via
[kubernetes-incubator/bootkube](https://github.com/kubernetes-incubator/bootkube))
* Fully self-hosted, including the kubelet
