Explain Billing Address setup for company invoices

[monty241]

The readme is targeting B2C, but from the text itself it remains unclear how the billing address should be structured for an order for a company.

The billing address is recommended for some payment brands, but allows not both specification of company name and first / last name.

Also, often street name, house number and addition are not available in split format. Some recommendations whether a merged variant is allowed would be welcome.