Update ObjectPool.cs

Added the spawn function to the second constructor. This allows a number of objects to be pre-spawned.

Object Pool 2/ObjectPool.cs

@@ -17,6 +17,7 @@ public ObjectPool(GameObject pooledObject, Action<T> pullObject, Action<T> pushO
             this.prefab = pooledObject;
             this.pullObject = pullObject;
             this.pushObject = pushObject;
+            Spawn(numToSpawn);
         }
 
         private System.Action<T> pullObject;