doc(buttons): Add a comment about not using PB_Get

epicardium/modules/buttons.c

@@ -14,6 +14,7 @@ static void epic_buttons_update(uint8_t mask)
 		button_states[3] = MAX77650_getDebounceStatusnEN0();
 	}
 	if (portexpander_detected() && (mask % 8)) {
+	    /* Not using PB_Get() here as that performs one I2C transcation per button */
 		uint8_t button_status = portexpander_get();
 		for (int i = 0; i < 3; i++) {
 			button_states[i] = (button_status >> ButtonPin[i]) & 1;