Fix yamllint `document-start` occurrences.

roles/ipaclient/vars/RedHat-8.yml

roles/ipaclient/vars/default.yml

roles/ipareplica/meta/main.yml

roles/ipareplica/vars/Fedora-25.yml

roles/ipareplica/vars/Fedora-26.yml

roles/ipareplica/vars/Fedora-27.yml

roles/ipareplica/vars/Fedora.yml

roles/ipareplica/vars/RedHat-7.yml

roles/ipareplica/vars/RedHat-8.yml

roles/ipareplica/vars/Ubuntu.yml

roles/ipareplica/vars/default.yml

roles/ipaserver/meta/main.yml

roles/ipaserver/tasks/copy_external_cert.yml

roles/ipaserver/vars/Fedora-25.yml

roles/ipaserver/vars/Fedora-26.yml

roles/ipaserver/vars/Fedora-27.yml

roles/ipaserver/vars/Fedora.yml

roles/ipaserver/vars/RedHat-7.yml

roles/ipaserver/vars/RedHat-8.yml

roles/ipaserver/vars/Ubuntu.yml