Drupal Commerce: Print order for warehouse
You will want to use the Commerce Message module: https://www.drupal.org/project/commerce_message

This module provides a !order-summary token which embeds an order's line item summary. This token only works, however, if the Message bundle has the message_commerce_order field.

You can either programmatically add this to a new Message bundle. Or, the easy route, clone the default admin notification and adjust as needed!