Introducing new commands in episode 5

[DagobertTheCat]

I noticed that a bunch of the commands that are introduced in episode 5. Counting and Mining with the Shell are not explained. For example, the students have already used ls -lh but not ls -lhS and S is never explicitly called out as new, and what it stands for and what is does is not explained. This also happens with head -n 3 later on. While the students will be able to see what this does from the live coding, I think it would be useful to explain these a little more and provide opportunities for people to experiment with the commands a bit more. This is a very long episode compared to the others, so breaking it up with some additional activities could prevent information overload and fatigue.

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