harpia: update info

systems/phone_motorola_harpia/readme.md

@@ -27,3 +27,4 @@
 - a1 rated sd cards are highly recommended as otherwise the performance will be bad due to bad random disk io
 - if the phone is connected to a computer or power supply via usb a shutdown will result in a reboot, disconnecting it will let it shutdown properly
 - sometimes there the system was hanging during shutdown, tapping onto the screen a few times seems to help
+- in case of problems with the boot process the phone does not seem to respond to the power button anymore to turn it off, pressing the vol-down and the power button together for a while might help out in those situation