Content and styling review

[dwsilk]

First off, apologies, this PR has way more in it than one PR should.

@dnhansen50 and I have sat down for a couple of sessions to:

• flesh out content,
• improve the consistency of the styling,
• attempt to ensure that important stuff is easily accessible and some less important stuff is a little more out of the way

[alpha-beta-soup]

Damn, that's good work! I can't see any issues locally.

[alpha-beta-soup]

Merged with a --squash in https://github.com/foss4g-oceania/hoverboard/commit/d6742c616cef2cfbeeda477a4a8eefc47c655bc5