Test gitbook / github / openapi intregration

[alexgarel]

• create a new test repository (on Funke’s GitHub account, or we can create one on openfoodfacts account if needed)
• add an introduction md file
  • test modifying md file either from github or from gitbook
• an openapi file
  • document GET /api/v2/product/[barcode number]
  • integrate to gitbook
  • modify on github to see how gitbook handles it
• test loading openapi file generated from existing postmal documentation