🚸 Change M201 G to S

Marlin/src/gcode/config/M200-M205.cpp

 #endif // !NO_VOLUMETRICS
 
 /**
- * M201: Set max acceleration in units/s^2 for print moves (M201 X1000 Y1000)
+ * M201: Set max acceleration in units/s^2 for print moves.
  *
- *       With multiple extruders use T to specify which one.
+ *  X<accel> : Max Acceleration for X
+ *  Y<accel> : Max Acceleration for Y
+ *  Z<accel> : Max Acceleration for Z
+ *       ... : etc
+ *  E<accel> : Max Acceleration for Extruder
+ *  T<index> : Extruder index to set
+ *
+ * With XY_FREQUENCY_LIMIT:
+ *  F<Hz>      : Frequency limit for XY...IJKUVW
+ *  S<percent> : Speed factor percentage.
  */
 void GcodeSuite::M201() {
-  if (!parser.seen("T" STR_AXES_LOGICAL))
+  if (!parser.seen("T" STR_AXES_LOGICAL TERN_(XY_FREQUENCY_LIMIT, "FS")))
     return M201_report();
 
   const int8_t target_extruder = get_target_extruder_from_command();
 
   #ifdef XY_FREQUENCY_LIMIT
     if (parser.seenval('F')) planner.set_frequency_limit(parser.value_byte());
-    if (parser.seenval('G')) planner.xy_freq_min_speed_factor = constrain(parser.value_float(), 1, 100) / 100;
+    if (parser.seenval('S')) planner.xy_freq_min_speed_factor = constrain(parser.value_float(), 1, 100) / 100;
   #endif
 
   LOOP_LOGICAL_AXES(i) {