Changing "Containers used in generating this lesson" to have other examples

[sstevens2]

This came up in the March 2021 maintainers meeting. We thought this lesson might be better with a few options as an example. In this discussion thread we should discuss what other examples we might want to add and if we like some we can then make issues/PRs to add them.

Also mentioned in issue #76

P.S. Also testing out using a discussion thread for the first time

[sstevens2]

For a biology example - Maybe CheckM?
I made a container on dockerhub with it because I was tired of installing checkm on different machines and so my lab (at the time) could use it on the local computing cluster. It might need some minor updating but it has several software dependancies and then is a pip install for the final software. I did have to finish one of the setup steps interactively because I could not get it to work with a Dockerfile. That is a little unusual but could be a good motivator for discussion of how to commit a container.