[Examples] Add external example with typescript to "with-material-ui"…

… folder (#37846)

## Documentation / Examples

- Add external example with typescript to `with-material-ui` folder as suggested on PR below.

[older PR related](#37499)

Co-authored-by: Balázs Orbán <18369201+balazsorban44@users.noreply.github.com>

examples/with-material-ui/README.md

@@ -1,3 +1,6 @@
-# Material UI example
+# Material UI examples
 
-This example have been moved here: [mui/material-ui](https://github.com/mui/material-ui/tree/master/examples/nextjs)
+**Note:** These examples are maintained outside of the Next.js repository:
+
+1. Official [TypeScript example](https://github.com/mui/material-ui/tree/master/examples/nextjs-with-typescript)
+2. Official [JavaScript example](https://github.com/mui/material-ui/tree/master/examples/nextjs)