Review book to remove instructions (i.e. not guidance)

[foster999]

Parts of the book (version control in particular) contain instructions on how to use tools. Where possible, convert this to guidance that outlines good practices. Otherwise, remove content and create a reference to the tool's documentation for normal use.

Some other issues that fall under this:

• [ ] #147

[foster999]

We might make exceptions where no equivalent instructions are available elsewhere