🔧 Fix Skew Correction defaults (#24601)

Marlin/Configuration.h

@@ -2134,9 +2134,8 @@
   #define XY_DIAG_BD 282.8427124746
   #define XY_SIDE_AD 200
 
-  // Or, set the default skew factors directly here
+  // Or, set the XY skew factor directly:
-  // to override the above measurements:
+  //#define XY_SKEW_FACTOR 0.0
-  #define XY_SKEW_FACTOR 0.0
 
   //#define SKEW_CORRECTION_FOR_Z
   #if ENABLED(SKEW_CORRECTION_FOR_Z)
@@ -2145,8 +2144,10 @@
     #define YZ_DIAG_AC 282.8427124746
     #define YZ_DIAG_BD 282.8427124746
     #define YZ_SIDE_AD 200
-    #define XZ_SKEW_FACTOR 0.0
+
-    #define YZ_SKEW_FACTOR 0.0
+    // Or, set the Z skew factors directly:
+    //#define XZ_SKEW_FACTOR 0.0
+    //#define YZ_SKEW_FACTOR 0.0
   #endif
 
   // Enable this option for M852 to set skew at runtime