Version the Documentation

[lapp0]

Fixes https://github.com/outlines-dev/outlines/issues/999

Changes

Versions the documentation using mike.

Demo:

• Site: https://lapp0.github.io/outlines/
• Branch: https://github.com/lapp0/outlines/tree/gh-pages

Behavior:

• Doesn't backfill documentation versioning.
• Has drop-down for version history, including all versions starting with the next release
• Version dropdown: "main / unstable", followed by "[latest version number] / stable", followed by all prior versions
• / redirects to /stable
• breaks any external links to documentation
  • e.g. https://outlines-dev.github.io/outlines/reference/json_mode/ is now https://outlines-dev.github.io/outlines/latest/reference/json_mode/

Set Up

Must have https://github.com/outlines-dev/outlines/settings/pages set to "deploy from a branch" with branch of gh-pages

Must cut a release after merging for the following reason:

• After merging this PR:

  • 404: https://outlines-dev.github.io/outlines/
  • 404: https://outlines-dev.github.io/outlines/latest
  • 200: https://outlines-dev.github.io/outlines/unstable

• After cutting a release

  • 302: https://outlines-dev.github.io/outlines/ -> https://outlines-dev.github.io/outlines/latest
  • 200: https://outlines-dev.github.io/outlines/latest