Docs for using the CLI, as a non-admin user

[eschwartz]

Our dce-cli docs are focused on admin users, with information on how to deploy DCE using the CLI. But I can't find any docs for non-admin users, just how on how to start using the CLI (eg, to create a lease)

https://dce.readthedocs.io/en/latest/howto.html#use-the-dce-cli

In short, we need to show how to configure the hostname of the DCE API.