Clarify that LEGO_EMAIL must be routable.
If the email provided for LEGO_EMAIL is not a valid, routable email address, Let's Encrypt ACME me calls will fail, and without error from the kube-lego
container.
Mesages like the following show that LE is rejecting your requests silently.
2017-02-15T17:20:57.441814450Z time="2017-02-15T17:20:57Z" level=info msg="creating new secret" context=secret name=gitlab-tls namespace=gitlab
2017-02-15T17:20:57.444901346Z time="2017-02-15T17:20:57Z" level=error msg="Error while process certificate requests: Secret \"gitlab-tls\" is invalid: [data[tls.crt]: Required value, data[tls.key]: Required value]" context=kubelego