Add doc on: Creating custom cart form associated with an order type

[j2s]

I'd be happy to add to docs but not sure how...

• Duplicate the standard form View commerce_cart_form
• Name as Cart form my 1 (machine name could be cart_form_my1)
• Adjust layout/format as required
  note: click Edit view name/description and see Administrative tag is commerce_cart_form - this is used in Order type edit form to find cart forms to select from
• Go to edit Order type and new cart form will show up in drop down – select it - save
• Refresh cart and see new layout!