Following construct:

{{< bpmn-viewer name="sample-process" >}}

used in .md file must display the BPMN diagram, but it doesn't.

See examples here:
https://blog.camunda.org/post/2016/08/kpi-monitoring-with-camunda/
https://blog.camunda.org/post/2016/12/conways-game-of-life/

and on attached screenshots.