Right now there is some CORS code in the demo app but it's probably better to move that to the ingress so people don't need to worry about reimplementing that in their backend service, especially if they choose to write it in a different language.
The annotations can be added to ingress.yml like this:

nginx.ingress.kubernetes.io/enable-cors "true"
nginx.ingress.kubernetes.io/cors-allow-origin "https://something.com/"