ejabberd configuration

Reference documentation: https://docs.ejabberd.im/admin/configuration)
Crowd
- ejabberd.example.yml from: https://raw.githubusercontent.com/processone/ejabberd/master/ejabberd.yml.example
- ejabberd-blog.yml from the process-one blog: https://www.process-one.net/blog/ejabberd-xmpp-server-useful-configuration-steps/
- ejabberd_template.yml from: https://raw.githubusercontent.com/processone/ejabberd-ecs-azure/master/conf/ejabberd_template.yml
- ejabberd-kuketz.yml from the kuketz blog: https://www.kuketz-blog.de/ejabberd-installation-und-betrieb-eines-xmpp-servers/
- ejabberd-v1.0.yml version 1.0 from this repository