Make sure we document setting the hostname for cluster or client/server scenarios

[tas50]

The hostname config in suites is a super powerful way to utilize the single dokken network and docker name resolution for cluster or client/server configurations. We should document how to do that.

[davidalpert]

is this sufficient, to set driver.hostname_alias in .kitchen.yml?

• https://github.com/test-kitchen/kitchen-dokken#adding-hostname-aliases

or is there more setup which is required?