readme.rst improvements: Quickstart guide

[degville]

• added a Quickstart guide to the beginning
• tweaked early structure and intro

The motivation for this is help people get up and running to test the Starter pack as quickly as possible, without having to skip through what's currently a large body of text.

[degville]

LGTM

Suggested next steps:

• dial down echoing, which is neat but probably confusing

Thanks. I think you're right. I'll replace these elements after it's been merged.

• alpha-docs > <new-repository-name> (or somesuch)

Yep, ok - thanks. I chose this as it's used later on in the readme.

[degville]

Thanks @ru-fu. I'll include all your suggestions in a follow-up. I'll put this together quickly, along with Daniele's suggestions.