More Docker and Kubernetes Getting Started Resources

Some more tutorials to help people get started.

README.md

@@ -83,8 +83,15 @@ The [Release Process](docs/governance/release_process.md) documentation displays
 
 Agones is in active development - we would love your help in shaping its future!
 
-## This all sounds great, but can you explain Kubernetes to me?
-[You should totally read this comic, and interactive tutorial](https://cloud.google.com/kubernetes-engine/kubernetes-comic/)
+## This all sounds great, but can you explain Docker and/or Kubernetes to me?
+
+### Docker
+- [Docker's official "Getting Started" guide](https://docs.docker.com/get-started/)
+- [Katacoda's free, interactive Docker course](https://www.katacoda.com/courses/docker)
+
+### Kubernetes
+- [You should totally read this comic, and interactive tutorial](https://cloud.google.com/kubernetes-engine/kubernetes-comic/)
+- [Katacoda's free, interactive Kubernetes course](https://www.katacoda.com/courses/kubernetes)
 
 ## Licence