Document a "Consumer" Learning Path

[sk8forether]

Create a short document for the "Consumers" of containers (people who do not develop their own containers and software, but use existing images) to navigate working with the Singularity templates in the CTL to pull, build, and run the container images on XSEDE systems and XSEDE-like clusters. Should be written for the audience that does not need to know the ins and outs of container development or image management.