Add API for features

[jamesnw]

This adds a simple static api to the GitHub Pages site.

• /api/v1/features.json returns a list of all keys.
• /api/v1/features/[id].json returns a single feature (with the addition of the id).

We could easily add additional endpoints down the road.

While there is an API available at https://api.webstatus.dev/v1/features/[id], I think this has some benefits-

• Anyone can (very) simply host their own version
• The returned data is in the same format as the web-features data (the webstatus.dev API renames fields and changes the structure slightly)
• We have better control over the update cadence

@tidoust says it better here- #204 (comment).

This does add a dependency from the gh-pages submodule on packages/web-features, and I think currently the API would get updated whenever the gh-pages repo is updated. We need to consider if the API should be updated with every update to main, or only on releases.

• Document API
• Configure API update cadence

[captainbrosset]

Love it. 🛳️ it