Add TODO to prompt user if extruder is extruding correct color

Firmware/mmu2.cpp

@@ -356,6 +356,10 @@ bool MMU2::load_filament_to_nozzle(uint8_t index) {
         SetActiveExtruder(0);
 
         Sound_MakeSound(e_SOUND_TYPE_StandardConfirm);
+
+        // TODO: The LCD should prompt the user with a full-screen message
+        //       to ask whether the extruder is extruding the correct color.
+        //       This does not apply when the tool change is done via gcode.
         return true;
     }
 }