Move usage documentation to separate page

[james-pre]

The usage documentation takes up most of the readme. It will be cleaner if this is moved to its own dedicated page, which can be linked to from the readme.

[jeff-hykin]

Usage on the readme is my favorite (like deno dax is one of my favorite documentation examples). Full docs somewhere else is fine, but I'd ask to keep at least a couple main-usecase examples in the readme.

[james-pre]

I've actually been thinking about moving to some more visually appealing documentation for a while— specifically Starlight. However that will take quite some work.