add some comments

Code/Feather_Code_Test/feather_main_test_PID_April_Tag/feather_main_test_PID_April_Tag.ino

@@ -170,7 +170,7 @@ void moveVertical(int vel){
       // changed 
       motorVertical_L->setSpeed(abs((int) vel));
       motorVertical_R->setSpeed(abs((int) vel)); 
-      motorVertical_L->run(BACKWARD);
+      motorVertical_L->run(BACKWARD); 
       motorVertical_R->run(FORWARD);
       // changed
     } else if(vel < 0) { //down
@@ -198,14 +198,14 @@ void moveHorizontal(int vel_hori,int base_speed){
   int rspeed = vel_hori + base_speed;
 
   if (lspeed > 0){  
-    motorLeft->run(BACKWARD);
+    motorLeft->run(BACKWARD); // make it move forward 
   } else {
-    motorLeft->run(FORWARD);
+    motorLeft->run(FORWARD); 
   }
   if (rspeed > 0){
-    motorRight-> run(FORWARD);
+    motorRight-> run(FORWARD); 
   } else {
-    motorRight-> run(BACKWARD);
+    motorRight-> run(BACKWARD); // make it move backward
   }
   displaySpeed(lspeed, rspeed);
   motorLeft->setSpeed(min(MAX_SPEED, abs(lspeed )));