title: how to get the size of product to the cart page
body: <p>I have size of product (XS, XL, ...).</p>
  
  <p>I want add column in cart table Size, where show sizes of products.</p>
  
  <p>I added SKU in this table $_item->getSku(); This works.
  But $_item->getSize(); not works. Please, help me.</p>