Consider adding GUI tools to docker instructions

[mrjones-plip]

Recently had an orphaned sub title for " Use Kitematic (GUI for Docker tools)" on the Docker page. Since there was no content for this subtitle, we removed it.

However, maybe we want to add information about using a GUI to manage docker? This might be helpful for those less comfortable with both Docker and the command line. Here's a link for Kitematic.

[jkuester]

@mrjones-plip, now that Docker Desktop is available for all platforms (and is our recommended approach) do you think we can close this issue?

[mrjones-plip]

ah - yeah - good call!