update quickstart to add k3d (#1334)

Author: balibebas

docs/quickstart.md

@@ -11,7 +11,7 @@ solutions:
 
 * [minikube](https://github.com/kubernetes/minikube/releases), which creates a
   single-node K8s cluster inside a VM (requires KVM or VirtualBox),
-* [kind](https://kind.sigs.k8s.io/), which allows creating multi-nodes K8s
+* [kind](https://kind.sigs.k8s.io/) and [k3d](https://k3d.io), which allows creating multi-nodes K8s
   clusters running on Docker (requires Docker)
 
 To interact with the K8s infrastructure install it's CLI runtime [kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/#install-kubectl-binary-via-curl).