docs: Note PROBE_CALIBRATE results invalidated on motion system update

Any hardware change to the hotend or probe, change to the kinematics,
or change to the bed tilt is likely to invalidate the results of
PROBE_CALIBRATE.  Try to warn the user of that.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

docs/Delta_Calibrate.md

@@ -30,6 +30,13 @@ automatic probe has a bias of more than 25 microns (.025mm) then use
 manual probing instead. Manual probing only takes a few minutes and it
 eliminates error introduced by the probe.
 
+If using a probe that is mounted on the side of the hotend (that is,
+it has an X or Y offset) then note that performing delta calibration
+will invalidate the results of probe calibration. These types of
+probes are rarely suitable for use on a delta (because minor effector
+tilt will result in a probe location bias). If using the probe anyway,
+then be sure to rerun probe calibration after any delta calibration.
+
 Basic delta calibration
 =======================
 
@@ -228,3 +235,15 @@ Additional notes
   errors elsewhere in the hardware. For example, small differences in
   arm length may result in a tilt to the effector and some of that
   tilt may be accounted for by adjusting the arm length parameters.
+
+Using Bed Mesh on a Delta
+=========================
+
+It is possible to use [bed mesh](Bed_Mesh.md) on a delta. However, it
+is important to obtain good delta calibration prior to enabling a bed
+mesh. Running bed mesh with poor delta calibration will result in
+confusing and poor results.
+
+Note that performing delta calibration will invalidate any previously
+obtained bed mesh. After performing a new delta calibration be sure to
+rerun BED_MESH_CALIBRATE.