Lesson structure updates - episode size

[jcohen02]

This material was originally developed to be taught alongside a set of Docker material which is now the docker-introduction lesson.

It has been structured as 4 episodes that were taught online as the second day of a "Containers for reproducible research" course. The material filled two 2-hour sessions (including breaks and time for exercises).

Should the material be broken down into a larger number of smaller episodes or is having 4 episodes of 45-60 minutes each (including exercise and break time) reasonable?

[jcohen02]

This has been unintentionally duplicated in #5 so the discussion will be continued there and this issue is being closed.