[oniro] Request to enable plantuml in gitlab

Summary

We'd like to have PlantUML based diagrams in our projects

What is the current bug behavior?

Currently plantuml is not enabled and plantuml related markdown

doesn't work

What is the expected correct behavior?

plantuml sections interpreted and uml diagrams working

Either use http://www.plantuml.com/plantuml server or start your own.

Example: