Provide a set of sample workflow definitions to pick and run

[tsurdilo]

What would you like to be added:

Add sample workflow definitions and example use-cases

Why is this needed:

For demos and getting started experience for new users, it would be nice to
have a list of sample workflow definitions users can just pick and run (don't have to create themselves).

[cdavernas]

Closing this issue as won't fix because demo workflows can be picked from the website and be directly installed using synctl.
Proceeding otherwise might imo create overhead for all the users who do not care about the demo.