Create creator-oriented subsections in the docs for easier navigation

[VanDavv]

• “Getting started” (the simplest app that works and can be tested, described),
• “Quickstart” (from bare machine to working code in 5 minutes, for someone who knows what he’s doing or someone in a hurry or someone who doesn’t care),
• “Cheat Sheet” (I don’t remember what I’m looking for, API listing with one sentence description of a member)