chore: Docusaurus with webpack 5

[slorber]

Use an unreleased version of Docusaurus to test the webpack5 support works for this site, detect potential problems, and perf improvements.

See also facebook/docusaurus#4089

Perf improvements

• First build (local): 300s
• Second build (local): 90s

To get the benefits, it requires caching node_modules/.cache.
It is not possible in GH actions, so I suggest migrating the site to Netlify and use the appropriate toml config (example: https://github.com/react-navigation/react-navigation.github.io/pull/974/files)

---

Unrelated suggestion: Relay has a lot of versions and long build/start times

Assuming nobody ever edit Relay docs of 2 years ago, you can improve the DX by limiting the number of versions display in dev with this docs plugin config:

          onlyIncludeVersions:
            (isDev || isDeployPreview)
              ? ['current', ...versions.slice(0, 2)]
              : undefined,

For faster prod build, you can also move older docs to standalone deployments and link to them (see Jest for versions < 25 => https://jestjs.io/)

[slorber]

ready for review

[facebook-github-bot]

@jstejada has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[facebook-github-bot]

@jstejada has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[jstejada]

nvm i was making a mistake, attempting to land this locally now

[facebook-github-bot]

@jstejada merged this pull request in 4709cd1.

[christianvuerings]

@jsteiner @slorber I think this change causes an issue with zIndexes on the relay docs site:

[slorber]

Hi I'm sorry but I'm in holiday until 1st June I believe this is some custom css on relay, as other docusaurus sites don't have this problem Le ven. 21 mai 2021 à 16:16, Christian Vuerings ***@***.***> a écrit :

…

@jsteiner <https://github.com/jsteiner> @slorber <https://github.com/slorber> I think this change causes an issue with zIndexes on the relay docs site: [image: image] <https://user-images.githubusercontent.com/127199/119151401-35317000-ba04-11eb-8d75-2ff3524867bb.png> — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#3469 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAFW6PWORYI7DKHRQWFG7EDTOZTKNANCNFSM43ON326Q> .

[slorber]

Fixing website CSS issue in #3505