Add another nice arkade tutorial

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

README.md

@@ -212,6 +212,7 @@ arkade install inlets-operator \
 #### Community posts
 
 * [A bit of Istio before tea-time](https://blog.alexellis.io/a-bit-of-istio-before-tea-time/) - Alex Ellis
+* [Kubernetes: Automatic Let's Encrypt Certificates for Services with arkade](https://medium.com/@admantium/kubernetes-automatic-lets-encrypt-certificates-for-services-2a5f4aa7f886)
 * [Introducing Arkade - The Kubernetes app installer](https://blog.heyal.co.uk/introducing-arkade/) - Alistair Hey
 * [Portainer for kubernetes in less than 60 seconds!!](https://www.portainer.io/2020/04/portainer-for-kubernetes-in-less-than-60-seconds/) - by Saiyam Pathak
 * [Video walk-through with DJ Adams - Pi & Kubernetes with k3s, k3sup, arkade and OpenFaaS](https://www.youtube.com/watch?v=ZiR3QEfBivk)