[Feature] Have a warning on changing RF TX pins on pre-defined boards

[nullstalgia]

Pre-submission checklist

• [X] I checked that there is no other Feature Request describing my wish.
• [X] I checked that this feature is, in fact, not supported.
• [X] I accept that this issue may be closed if any of the above are found to be untrue.

What should be possible that currently is not?

For boards like PiShock Lite/2023 or my own PCBs, a user changing the RF TX pin should be discouraged/warned against.

Currently the only relevant information is on the Wiki, and having the pins pre-set in the UI during setup.

I think the only thing that's missing at this point is a warning stating that the pin has already been set by their choice of firmware, and that changing it is not recommended.

For generic WEMOS, Seeed, etc dev boards, leaving the RF pin undefined in the platformio.ini could be used as a way to suppress that warning, letting the user enter their chosen pin.

Other remarks

No response