Portal API specifications

1. Use Case

1.1 User Scenarios

As a platform developer I need to understand what I need to provide to the portal and how.

1.2 Business Motivation

Both Shopify and OFN team are awaiting this info (and I guess it was used for the locavora integration?)

2. Expected Outcome

2.1 Benefits for the User

A clear documentation to be able to deliver something coherent with other platforms

2.2 Success Criteria

Platforms are able to provide their DFC API in a correct format.

4. Acceptance Criteria

The documentation can be done in a wiki or the portal's repo readme. It needs to be reviewed by OFN and Yalla before considering done.