The `site.yml` playbook imports all of the other playbooks, providing a
way to deploy _everything_. Normally, this would only be done for a
single host, as part of its initial provisioning, to quickly apply all
common configuration and any application-specific configuration for
whatever roles the host happens to hold.
The `host-setup.yml` playbook provides an entry point for configuring
all common configuration. Basically anything we want to do to _every_
machine, regardless of its location or role.
Dustin