Update pin_defs.h (#120)

change the servo pin defs according to new sra board

Author: mt-tass

include/pin_defs.h

@@ -96,10 +96,10 @@
 /////////////////////////////
 
 /////////// servos //////////
-#define SERVO_A 15
-#define SERVO_B 5
-#define SERVO_C 19
-#define SERVO_D 18
+#define SERVO_A 15 //GRIPPER
+#define SERVO_B 5  //ELBOW
+#define SERVO_C 18 //ARM
+#define SERVO_D 19 //BASE
 /////////////////////////////
 
 //////// led matrix /////////
@@ -109,4 +109,4 @@
 #define SHIFT_REGISTER_RCLK  13
 /////////////////////////////
 
-#endif
+#endif