Suggestion for prereqs page

[jtr13]

Move the section on git down and the one on package development tools up. Emphasize more clearly that the tools are essential for package development while git is not.

If there's agreement, I can propose edits.

[EllaKaye]

Agree!

Might be worth noting that whilst git/GitHub isn't essential for package development, it is best practice and we will be making use of GitHub features during the course, e.g. publishing a package documentation website using GitHub pages.

[jtr13]

Great suggestion. Just opened a PR. If there's anything I didn't get quite right, please feel free to reword.