Deis had published an easy to understand version of Kubernetes guide calling Children's Illustrated Guide to Kubernetes
It explains Containers and the need for container management pretty well. It focuses on Kubernetes. There are other container orchestration systems like DCOS that provide the same capabilities of container orchestration as explained in that guide.
The character rendering, which include, PHP app as a giraffe, Kubernetes as a ship captain, docker as whale, gopher as go lang app, elephant as postgresql app were great.