Instructions from: https://www.digitalocean.com/community/tutorials/how-to-set-up-an-nginx-ingress-with-cert-manager-on-digitalocean-kubernetes Source: https://github.com/jetstack/cert-manager
there was a password.txt file in here. Not in git for obvious reasons.
--- And after october 2021, none of that worked, and instead:
kubectl apply -f https://github.com/jetstack/cert-manager/releases/download/v1.5.4/cert-manager.yaml