Let's now implement the "Edit Product"
functionality of our site. We'll ultimately want users to see a screen
like below when they visit the /Products/Edit/[ProductID] URL:
Like the "Add New Product" form post example
above, we are going to implement this form edit interaction using two
ProductsController Actions that we'll call "Edit" and
"Edit" will display the product form.
"Update" will be used to handle the form's submit action.