delta: Added the possibility to get where the "cone shape" of the build volume starts from Macros (#5662)

Added the possibility to get where the "cone shape" of the build volume starts from Macros

Signed-off-by: Martin Malmqvist <Volcomosq@gmx.com>

klippy/kinematics/delta.py

@@ -150,6 +150,7 @@ class DeltaKinematics:
             'homed_axes': '' if self.need_home else 'xyz',
             'axis_minimum': self.axes_min,
             'axis_maximum': self.axes_max,
+            'cone_start_z': self.limit_z,
         }
     def get_calibration(self):
         endstops = [rail.get_homing_info().position_endstop