Add 0 to EXTRUDERS :[json] (#18786)

Marlin/Configuration.h

@@ -141,7 +141,7 @@
 // @section extruder
 
 // This defines the number of extruders
-// :[1, 2, 3, 4, 5, 6, 7, 8]
+// :[0, 1, 2, 3, 4, 5, 6, 7, 8]
 #define EXTRUDERS 1
 
 // Generally expected filament diameter (1.75, 2.85, 3.0, ...). Used for Volumetric, Filament Width Sensor, etc.