Follow-up the PR #4271 (X_DUAL_STEPPER_DRIVERS)

・Update a forgotten Configuration_adv.h of K8400

Marlin/example_configurations/K8400/Configuration_adv.h

@@ -229,11 +229,28 @@
 
 //#define Z_LATE_ENABLE // Enable Z the last moment. Needed if your Z driver overheats.
 
+// Dual X Steppers
+// Uncomment this option to drive two X axis motors.
+// The next unused E driver will be assigned to the second X stepper.
+//#define X_DUAL_STEPPER_DRIVERS
+#if ENABLED(X_DUAL_STEPPER_DRIVERS)
+  // Set true if the two X motors need to rotate in opposite directions
+  #define INVERT_X2_VS_X_DIR true
+#endif
+
+
+// Dual Y Steppers
+// Uncomment this option to drive two Y axis motors.
+// The next unused E driver will be assigned to the second Y stepper.
+//#define Y_DUAL_STEPPER_DRIVERS
+#if ENABLED(Y_DUAL_STEPPER_DRIVERS)
+  // Set true if the two Y motors need to rotate in opposite directions
+  #define INVERT_Y2_VS_Y_DIR true
+#endif
+
 // A single Z stepper driver is usually used to drive 2 stepper motors.
-// Uncomment this define to utilize a separate stepper driver for each Z axis motor.
+// Uncomment this option to use a separate stepper driver for each Z axis motor.
-// Only a few motherboards support this, like RAMPS, which have dual extruder support (the 2nd, often unused, extruder driver is used
+// The next unused E driver will be assigned to the second Z stepper.
-// to control the 2nd Z axis stepper motor). The pins are currently only defined for a RAMPS motherboards.
-// On a RAMPS (or other 5 driver) motherboard, using this feature will limit you to using 1 extruder.
 //#define Z_DUAL_STEPPER_DRIVERS
 
 #if ENABLED(Z_DUAL_STEPPER_DRIVERS)
@@ -255,14 +272,6 @@
 
 #endif // Z_DUAL_STEPPER_DRIVERS
 
-// Same again but for Y Axis.
-//#define Y_DUAL_STEPPER_DRIVERS
-
-#if ENABLED(Y_DUAL_STEPPER_DRIVERS)
-  // Define if the two Y drives need to rotate in opposite directions
-  #define INVERT_Y2_VS_Y_DIR true
-#endif
-
 // Enable this for dual x-carriage printers.
 // A dual x-carriage design has the advantage that the inactive extruder can be parked which
 // prevents hot-end ooze contaminating the print. It also reduces the weight of each x-carriage