#3507892 Checkout: add a step description to the default contact information step (1)

This add a description to the billing information step for carts without a domain.

To test:

• visit checkout without a domain in your cart
• verify that the second step has the following description: “Entering your billing information helps us prevent fraud.”
• add a domain to your cart
• verify that the second step has the following description: “Registering a domain name requires valid contact information. Privacy Protection is included for all eligible domains to protect your personal information.”