Examples - Updated with-windcss example for App Router (#69365)
This PR updates the with-windcss example to use the App Router. Here are
the changes that have been made:
- Renamed the "pages" folder to "app" folder.
- Updated the file index.tsx to page.tsx to align with App Router
- Added the layout.tsx file as part of the App Router.
- removed <Head> tag
- updated package versions
cc @samcx
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Co-authored-by: Sam Ko <sam@vercel.com>
