Fix anycubic i3 mega gcode comments

resources/definitions/anycubic_i3_mega.def.json

@@ -58,7 +58,7 @@
         },
         "machine_end_gcode":
         {
-            "default_value": "M104 S0 ; turn off extruder\nM140 S0 ; turn off bed\nM84 ; disable motors\nM107\nG91 ;relative positioning\nG1 E-1 F300 ;retract the filament a bit before lifting the nozzle\nto release some of the pressure\nG1 Z+0.5 E-5 ;X-20 Y-20 F{speed_travel} ;move Z up a bit and retract filament even more\nG28 X0 ;Y0 ;move X/Y to min endstops\nso the head is out of the way\nG1 Y180 F2000\nM84 ;steppers off\nG90\nM300 P300 S4000"
+            "default_value": "M104 S0 ; turn off extruder\nM140 S0 ; turn off bed\nM84 ; disable motors\nM107\nG91 ;relative positioning\nG1 E-1 F300 ;retract the filament a bit before lifting the nozzle, to release some of the pressure\nG1 Z+0.5 E-5 ;X-20 Y-20 F{speed_travel} ;move Z up a bit and retract filament even more\nG28 X0 ;Y0 ;move X/Y to min endstops, so the head is out of the way\nG1 Y180 F2000\nM84 ;steppers off\nG90\nM300 P300 S4000"
         }
     }
 }