[docs] Added per page layout example with TypeScript (#27488)
[docs] Added per page layout example with TypeScript (#27488)

## Documentation / Examples

- [x] Make sure the linting passes

## Explanation
Fixes #27465 

I added some docs on how to use per page persistent layouts in TypeScript as this requires you to extend some types and it might not be trivial if you are just starting out with TypeScript.

I copied the js example so it might be better to remove some of the duplication where possible, let me know.
All feedback is welcome


zeit/next.js,zeit/next.js,azukaru/next.js,flybayer/next.js,JeromeFitz/next.js,zeit/next.js,JeromeFitz/next.js,JeromeFitz/next.js,azukaru/next.js,azukaru/next.js,flybayer/next.js,azukaru/next.js,flybayer/next.js,JeromeFitz/next.js,flybayer/next.js