Add more Notes and a gcode_z_offset example

wiki/Calibration.md

@@ -1,9 +1,11 @@
 ## Z Offset
 
+**NOTE:** `gcode_z_offset` on Tool 0 is always 0.
+
 - Home and QGL
 - Set the tool `z_offset` using the paper method
 - Add this to the tool_probe config `z_offset`
-- For tools after 0, use this value to find the `gcode_z_offset`, which is the difference between this `tool_probe` and `tool_probe` for tool 0 `z_offset`.
+- For tools after Tool 0, use this value to find the `gcode_z_offset`, which is the difference between this `tool_probe` and `tool_probe` for tool 0 `z_offset`. ie: if Tool 1 has a `z_offset` of `1.0` and Tool 0 is `0.8`, the `gcode_z_offset` for Tool 1 is `-0.2`
 - Restart Klipper
 - Repeat for all tools
 
@@ -21,6 +23,6 @@
 
 ## X/Y Offset
 
-**Only for tools after 0, T0 will always be 0**
+**NOTE:** `gcode_x_offset` and `gcode_y_offset` on Tool 0 are always 0.
 
 Coming Soon™