Request: updated Handbook homepage in line with new Docs homepage style

[charlescook-ph]

@pjhul did a beautiful job with the new Docs homepage. It would be really cool if the Handbook homepage had the same look to it - could 'just' be the six tiles section, covering:

• Start here
• Team - maybe I'd call this 'who's who' to avoid repeating 'team' below
• Culture
• Strategy
• Communication
• Team structure

(Definitely one of those 'if someone is bored and has some time' low priority type requests though...)

[corywatilo]

We should be able to repurpose the upcoming dropdown menu for this.