Add EXTRA_FAN_SPEED feature

Marlin/example_configurations/TinyBoy2/Configuration_adv.h

@@ -810,6 +810,15 @@
   #define RETRACT_RECOVER_FEEDRATE_SWAP 8 // Default feedrate for recovering from swap retraction (mm/s)
 #endif
 
+/**
+ * Extra Fan Speed
+ * Adds a secondary fan speed for each print-cooling fan.
+ *   'M106 P<fan> T3-255' : Set a secondary speed for <fan>
+ *   'M106 P<fan> T2'     : Use the set secondary speed
+ *   'M106 P<fan> T1'     : Restore the previous fan speed
+ */
+//#define EXTRA_FAN_SPEED
+
 /**
  * Advanced Pause
  * Experimental feature for filament change support and for parking the nozzle when paused.