feat: have .tsx be in ts template for create-next-app (#25820)

Signed-off-by: Matthew Gleich <git@mattglei.ch>

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>
Co-authored-by: Tim Neutkens <tim@timneutkens.nl>

packages/create-next-app/templates/typescript/README-template.md

@@ -12,9 +12,9 @@ yarn dev
 
 Open [http://localhost:3000](http://localhost:3000) with your browser to see the result.
 
-You can start editing the page by modifying `pages/index.js`. The page auto-updates as you edit the file.
+You can start editing the page by modifying `pages/index.tsx`. The page auto-updates as you edit the file.
 
-[API routes](https://nextjs.org/docs/api-routes/introduction) can be accessed on [http://localhost:3000/api/hello](http://localhost:3000/api/hello). This endpoint can be edited in `pages/api/hello.js`.
+[API routes](https://nextjs.org/docs/api-routes/introduction) can be accessed on [http://localhost:3000/api/hello](http://localhost:3000/api/hello). This endpoint can be edited in `pages/api/hello.tsx`.
 
 The `pages/api` directory is mapped to `/api/*`. Files in this directory are treated as [API routes](https://nextjs.org/docs/api-routes/introduction) instead of React pages.