Add changeBand to docs

[karlsoderby]

No description provided.

[kygoh]

Do you mean modem.configureBand() instead of modem.changeBand()?

MKRWAN/src/MKRWAN.h

Lines 470 to 479 in 4e786dd

	bool configureBand(_lora_band band) {
	sendAT(GF("+BAND="), band);
	if (waitResponse() != 1) {
	return false;
	}
	if (band == EU868 && isArduinoFW()) {
	return dutyCycle(true);
	}
	return true;
	}

[karlsoderby]

You're right @kygoh, just updated it. Thank you!