Note/Memo field added to generated invoices

When I am using the generate invoice for my customers it would be extremely helpful to have a place to add important notes for that individual customer, for example, since the generated invoice process does not note or apply any credits that may be available to the customer, this would be a great place to let the customer be aware of their true outstanding balance.

Therefore, as a note box was added to email receipts, this would also be helpful with system generated invoices