- Update InvoiceRequest notification_url definition to use SHOULD instead of MAY
- Capitalize MUST, SHOULD, etc.
- Update InvoiceRequest Message Creation steps to specifically define behavior for empty amount or amount out of bounds
- Add implementation section with references to Addressimo reference Store & Forward server and a client implementation in functest_ir.py
- Add flow diagrams for BIP70 extension and moble-to-mobile example with store and forward service
