feat(docs.rs): apply to doc.rust-lang.org

[MaximGY]

🔧 What does this fix? 🔧

Apply the docs.rs userstyle to https://doc.rust-lang.org (aka docs.rs/std)

🗒 Checklist 🗒

• [x] I have read and followed Catppuccin's contributing guidelines.
• [x] I have updated the version appropriately in the ==UserStyle== header of the catppuccin.user.css file.