Docs: Clarify correct usage of @radix-ui/themes/styles.css in JS vs CSS files

[Prince-Sharma-07]

The documentation currently shows this for adding Radix Themes styles:

import "@radix-ui/themes/styles.css";

This works when importing from JavaScript/TypeScript files (e.g. index.tsx, App.tsx, or layout.tsx).

But many developers try to include it inside a global CSS file (like globals.css in Next.js, or a root stylesheet in Vite/CRA/Remix). In that case, the syntax above is invalid, because import is not valid in CSS.

The correct syntax inside CSS files is:

@import "@radix-ui/themes/styles.css";

It would help if the docs clarified both usage patterns to avoid confusion across different frameworks.