Change retr0h.etcd to andrewrothstein.etcd-cluster

[patsevanton]

Please review pull request.

retr0h.etcd not supported and get error

Unable to start service etcd: Job for etcd.service failed because the control process exited with error code. See "systemctl status etcd.service" and "journalctl -xe" for details.

Nov 24 22:12:07 ubuntu etcd[17126]: --initial-cluster must include patroni3=http://127.0.0.1:2380 given --initial-advertise-peer-urls=http://127.0.0.1:2380
Nov 24 22:12:07 ubuntu systemd[1]: etcd.service: Main process exited, code=exited, status=1/FAILURE

[kostiantyn-nemchenko]

Merged, thank you!