Merge branch 'patch-3' into 'master'

Added QR-Code for Testflight

See merge request !29

app/developing.md

@@ -29,4 +29,4 @@ If you are able to create debug logs and create Issues feel free to subscribe th
 * flash that image on the card10
 * The ios-workarounds branch basically exposes all characteristics publicly, so everybody can connect to your card10 and read / write characteristic, so this is clearly only a development helper and not ment for day-to-day usage
 
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+[![https://testflight.apple.com/join/oqZhY70M](http://api.qrserver.com/v1/create-qr-code/?color=000000&bgcolor=FFFFFF&data=https%3A%2F%2Ftestflight.apple.com%2Fjoin%2FoqZhY70M&qzone=1&margin=0&size=400x400&ecc=L)](https://testflight.apple.com/join/oqZhY70M)