Undefined BOARD_ID resistances

[EanLombardo]

The framework 16 documentation is extremely thorough in defining what resistances result in what behavior for BOARD_ID pins.

But the framework 12 documentation does not define any resistances for the BOARD_ID pins.

[JohnAZoidberg]

For Laptop 16 the modules all have different resistances and that's how we detect which one is populated and if the input deck is fully covered.
On Laptop 12 and 13 we just detect "present" or "not present"