Remove nonexisting `color.saturate()` function

[FloEdelmann]

Only the non-prefixed (deprecated) saturate() function exists, as described a few lines below in the "Heads up" block.

[netlify[bot]]

✅ Deploy Preview for sass-lang ready!

Name	Link
🔨 Latest commit	d5e07af3501c7d089301c75c7ff6c2916f72bb3a
🔍 Latest deploy log	https://app.netlify.com/sites/sass-lang/deploys/66ebda230cb8ac000817d6f5
😎 Deploy Preview	https://deploy-preview-1190--sass-lang.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[nex3]

Thanks!