Trim main README

[kgar]

The main README should be trimmed down. Information such as extending the library and how options work are now documented in the project docs.

• Trim down the readme
• Generally link to the fuller documentation near the top of the readme
• Make mention of interesting things, but then link to specific pages in the documentation for more info
• Keep credits, why this project, and more high-level info like that in the readme
• Focus the readme on giving the quickest quick start info so that a person can grok this library at a glance

[kgar]

Replenish the typedocs when done, just to be sure the latest is out there.