feat: add global toggle for app and pages router to docs

[kakenbutter]

Is your feature request related to a problem? Please describe.

Currently, the docs are missing app router documentation and are lacking in a easy way to switch between app router and pages router documentation. I think in the long term, splitting pages into two parts (like the folder structure page) is not going to work.

Describe the solution you'd like to see

I would like to see more documentation for the app router (like updating the next.js page) as well as a toggle for switching between the app and pages router.

Describe alternate solutions

.

Additional information

No response