[WIP] Next.js back to x0

[shawnbot]

This is what it looks like to go back to using x0. I'm going to publish the docs to see if this can fix #59.

[shawnbot]

Well, this Pages deployment is closer than we were to having permalinks, but not quite there yet:

1. The component pages (Block, for example) don't include the library navigation.
2. Links in the nav have hrefs to the name of the example (Form%20elements) rather than to the file from which they're loaded (form-elements). Not sure if I understand what how kit works here.

[shawnbot]

Closing this since the x0 upgrade was done in #72. Let's take up fixing the permalink issues in a new branch.