feat(website): enable docs versioning

[ikatyang]

Fixes #5362 (by upgrading docusaurus)
Unblock #5674

v1 docs are generated by yarn docusaurus-version v1, which enables the docs versioning and copies the current docs to the v1 folder. We just need to run it again to sync the current docs and the next docs before releasing a new version.

cc @kachkaev

• I’ve added tests to confirm my change works.
• (If changing the API or CLI) I’ve documented the changes I’ve made (in the docs/ directory)
• I’ve read the contributing guidelines.

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[ikatyang]

I forgot the version field in package.json is changed after yarn build(fixed). Here's the expected output for https://deploy-preview-5676--prettier.netlify.com/versions.html:

[j-f1]

What do you think about calling it stable instead of v1? Once we release v2, the docs will then be available as stable, 1.x and next.

[j-f1]

Also, how will the docs be updated when releasing a new version?

[kachkaev]

Thanks for working on this @ikatyang and for cc-ing me! I don't have any experience with docusaurus or publishing several doc versions at once, so unfortunately can't express any useful opinion here. If using a single master branch and multi-versioned docs works well as multiple branches we were discussing in #5671, I'm happy with this decision.

[ikatyang]

Based on the discussion in #5671, I think it should be better to be in this form:

• stable: https://prettier.io/docs/en/index.html (deployed from master)
• next minor: https://prettier.io/docs/en/next/index.html (deployed from master)
• next major: https://next.prettier.io/docs/en/index.html (deployed from next branch)
• past major: https://v1.prettier.io/docs/en/index.html (deployed from v1 branch)

This PR aims to address stable and next minor, the major ones should be handled in v2.

[ikatyang]

Also, how will the docs be updated when releasing a new version?

yarn docusaurus-version <version-id> is the command to take a snapshot for the current docs for docs versioning, so we just need to run yarn docusaurus-version stable again to override stable with next (master).