docs: add PREFS website to showcase

[Patitotective]

Motivation

Help to improve docusaurus showcase section (and by the way promote PREFS).

Have you read the Contributing Guidelines on pull requests?

Yes.

Test Plan

Just added a new element to Users list in website/src/data/users.tsx and prefs.png to website/src/data/showcase.

(See https://github.com/facebook/docusaurus/pull/5984/files for the changed files).

[netlify]

✔️ [V2]
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🔨 Explore the source changes: c53dfa5

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😎 Browse the preview: https://deploy-preview-5984--docusaurus-2.netlify.app

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟠 Performance	85
🟢 Accessibility	98
🟢 Best practices	100
🟢 SEO	100
🟢 PWA	95

Lighthouse ran on https://deploy-preview-5984--docusaurus-2.netlify.app/

[Josh-Cena]

Thanks, your screenshot doesn't fill the entire container though:

Could you submit a taller image? It's better to overflow than underflow.

Also, interesting choice of choosing Docusuarus. I think Sphinx is more trending in the Python ecosystem

[Patitotective]

@Josh-Cena
Just updated showcase image, let me know if it works (if it doesn't please tell me which aspect ratio it should be)

---

Also, interesting choice of choosing Docusuarus. I think Sphinx is more trending in the Python ecosystem

Well, if you have seen Sphinx docs, they're so... ugly when Docusaurus is so pretty and of course, it supports versioning the exact way I need it, previously I was using readthedocs.io and the versions were Git tags so I wasn't able to modify a specific version (fix typos) with Docusaurus I have all I want.

[Josh-Cena]

Well, good choice of Docusaurus then 👍

Thanks again