docs: update Bed Mesh documentation

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/docs/Config_Reference.md b/docs/Config_Reference.md
index 1cc0bc8f..fa770408 100644
--- a/docs/Config_Reference.md
+++ b/docs/Config_Reference.md
@@ -966,10 +966,18 @@ Visual Examples:
 #   be applied to change the amount of slope interpolated. Larger
 #   numbers will increase the amount of slope, which results in more
 #   curvature in the mesh. Default is .2.
+#zero_reference_position:
+#   An optional X,Y coordinate that specifies the location on the bed
+#   where Z = 0.  When this option is specified the mesh will be offset
+#   so that zero Z adjustment occurs at this location.  The default is
+#   no zero reference.
 #relative_reference_index:
-#   A point index in the mesh to reference all z values to. Enabling
-#   this parameter produces a mesh relative to the probed z position
-#   at the provided index.
+#   **DEPRECATED, use the "zero_reference_position" option**
+#   The legacy option superceded by the "zero reference position".
+#   Rather than a coordinate this option takes an integer "index" that
+#   refers to the location of one of the generated points. It is recommended
+#   to use the "zero_reference_position" instead of this option for new
+#   configurations. The default is no relative reference index.
 #faulty_region_1_min:
 #faulty_region_1_max:
 #   Optional points that define a faulty region.  See docs/Bed_Mesh.md