feat: add nixos.wiki

[nekowinston]

🎉 Theme for NixOS Wiki 🎉

Theme for the unofficial NixOS Wiki

🗒 Checklist 🗒

• I have read and followed Catppuccin's submission guidelines.
• I have made a new directory underneath /styles/<name-of-website> containing the contents of the /template directory.
  • I have ensured that the new directory is in lower-kebab-case.
  • I have followed the template and kept the preprocessor as LESS.
• I have made sure to update the
  userstyles.yml
  file with information about the new userstyle.
• I have included the following files:
  • catppuccin.user.css - all the CSS for the userstyle, based on the
    template.
  • assets/mocha.webp, assets/macchiato.webp, assets/frappe.webp and
    assets/latte.webp - individual screenshots of the themed website, in all 4
    Catppuccin flavors.
  • catwalk.webp - image of all individual screenshots stitched together,
    generated via catwalk.

[aemogie]

Found an issue, btw (https://nixos.wiki/wiki/Nix_Cookbook)

[nekowinston]

Found an issue, btw (nixos.wiki/wiki/Nix_Cookbook)

That's an issue that only occurs when DarkReader is active, & sadly those elements have no other unique selectors other than *[style*="background-color: #C1E5FF"].
I guess we could take the GitHub-style approach of checking for html[data-darkreader-scheme="dark"] { content: "warning"; }

[nekowinston]

Added that warning & some more adjustments, should be all good to go.
The Wiki occasionally refers to an alternative theme called Vector (e.g. https://nixos.wiki/index.php?useskin=vector), but I won't bother theming that, since even the wiki itself always redirects to the default theme when navigating.