Add a chapter on different shells (& plugin managers)

[tobiasbueschel]

There are a lot of shells out there which can be a difficult landscape for newcomers to navigate. And while bash, zsh and powershell are popular and well known, there are also many others around: https://en.wikipedia.org/wiki/Comparison_of_command_shells

Perhaps adding a chapter on the history, a small comparison and practical examples could be useful? + once you get deeper into some of these shells you might also want to look into plugin managers e.g. for zsh - zplugin, antigen, antibody, zgen, zplugin, etc.

[dwmkerr]

There's a section planned (in the ./structure.md doc for this

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Interlude

The Linux and Shell Family Tree

There are lots of different flavours of Linux and Unix, and lots of different shells. This interlude takes a quick look at the Linux and Unix family tree, and the different shells which have evolved over time.

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I'll keep this issue open for brainstorming though!