[ic] Prevent from ordering more than is in stock

[Xin Xu]

>From previous post, I learned that you could use MaxQuantityField as the
following to archive this in version 4.9.x

MaxQuantityField  inventory:quantity


My catalog use built using 4.8.7, and lately I upgrade interchange to 4.9.7
(without rebuilding the catalog). Where should I added the above line to
take advantage the new feature?

Thanks
-Xin