Fix item handler documentation that says returning ItemStack.EMPTY is required (#4587)

src/main/java/net/minecraftforge/items/IItemHandler.java

@@ -60,7 +60,7 @@ public interface IItemHandler
      * @param slot     Slot to insert into.
      * @param stack    ItemStack to insert. This must not be modified by the item handler.
      * @param simulate If true, the insertion is only simulated
-     * @return The remaining ItemStack that was not inserted (if the entire stack is accepted, then return ItemStack.EMPTY).
+     * @return The remaining ItemStack that was not inserted (if the entire stack is accepted, then return an empty ItemStack).
      *         May be the same as the input ItemStack if unchanged, otherwise a new ItemStack.
      *         The returned ItemStack can be safely modified after.
      **/