The paragraph at the bottom of the reference page refers to a link to a GitHub README.md which is out of date.
"For more information, see the dcos-metrics repository documentation."
The architecture diagram referenced in the "dcos-metrics repository" link is out of date and does not refer to Telegraph. Also, the inclusion of the marathon JSONs to install Grafana and Prometheus are out of date as now you only have to run the "
dcos package install --yes grafana
dcos package install --yes prometheus
dcos marathon app add <proxy json>