Reorganize documentation on boards and ROM pinouts

[Bregalad]

OK so in the end, I guess since we have no way of knowing if the unused pins on +5V or GND are unued /CE or /OE signals or not, the logic would say we should show the names of the singal leading to the pin.

However, it seems more complicated to do it this way as it implies different pinouts for PRG and CHR.

The other way to go, would be to make pinouts with only the name of the signals, that is "Ax", "Dx", "CE", "/CE", "/OE", and that's all. Unused signals would be still specified as "+5V" or "GND" as we can't be very sure of their usage.

Because on most carts the /CE and /OE wiring is the same, a simple paragraph about it should be used, and exeptions (such as AOROM) should be mentionned next to the pinout (like it's already right now).