message: adds docstring to driver.fast_home
diff: @@ -333,7 +333,12 @@ class SmoothieDriver_3_0_0:
  return homed
  - def fast_home(self, axis=AXES, safety_margin=10):
  + def fast_home(self, axis, safety_margin):
  + ''' home after a controlled motor stall
  +
  + Given a known distance we have just stalled along an axis, move
  + that distance away from the homing switch. Then finish with home.
  + '''
  # move some mm distance away from the target axes endstop switch(es)
  self.set_speed()
  destination = {
  