doc: fixed call to mkcloud setuphost
doc: fixed call to mkcloud setuphost

Added -E flag to sudo to preserve environment. This allows to set
cloudpv as environment variable beforehand. This is only relevant if
mkcloud is called as normal user with sudo.

SUSE-Cloud/automation,gosipyan/automation,SUSE-Cloud/automation,aspiers/automation,gosipyan/automation,aspiers/automation,gosipyan/automation,SUSE-Cloud/automation,aspiers/automation,gosipyan/automation,aspiers/automation,SUSE-Cloud/automation