Add support for Formbot T-Rex3

Marlin/src/pins/pins.h

@@ -132,8 +132,10 @@
   #include "pins_AZTEEG_X3_PRO.h"     // ATmega2560                                 env:megaatmega2560
 #elif MB(ULTIMAIN_2)
   #include "pins_ULTIMAIN_2.h"        // ATmega2560                                 env:megaatmega2560
-#elif MB(FORMBOT)
-  #include "pins_FORMBOT.h"           // ATmega2560                                 env:megaatmega2560
+#elif MB(FORMBOT_TREX2)
+  #include "pins_FORMBOT_TREX2.h"     // ATmega2560                                 env:megaatmega2560
+#elif MB(FORMBOT_TREX3)
+  #include "pins_FORMBOT_TREX3.h"     // ATmega2560                                 env:megaatmega2560
 #elif MB(RUMBA)
   #include "pins_RUMBA.h"             // ATmega2560                                 env:megaatmega2560
 #elif MB(BQ_ZUM_MEGA_3D)