Proposal: do not cover Unix/bash/shell and Git command line

[k8hertweck]

I propose we remove both Unix and the git on the command line from the book. Chapters involved include:

• 02-filesystem
• 05-version-control-solo

Both of these happen to be mine, so I can make the appropriate modifications.

Advantages:

• More time and space to focus on various ways to perform tasks using R commands and/or the RStudio interface
• Fewer requirements for independent software to install (though we need to explore this fully for Windows)

Disadvantages:

• There are edge cases where command line may be required for some git operations. We can make a note of this, but say readers aren't likely to face them
• Most of us know and use the command line, so the book won't fully replicate our authentic coding experiences
• We may need to cover some additional R commands for inspecting and navigating files and directories?

[k8hertweck]

Agreement in meeting on 3 June 2021 that this is acceptable, and I'll handle it.