These are used to signal the start of the document in a stream of many
documents. As Ansible only supports one YAML document per file this is
unnecessary. About a third of our YAML documents already lacked these.
To simplify the archive role, split it up in the web serving part for
the archive-mirrors, gemini and keep the archive role for only the
archive operation. This simplifies the new role as only two lines are
required to setup the the archive mirror website.