Suggest adding a child task to sample_app

[ejtimmon]

Is your feature request related to a problem? Please describe.
Not related to a problem.

Describe the solution you'd like
A simple child task could be added to sample_app to demonstrate how a child task is created. If sample_app is intended to be a fully featured example/template, child tasks are a key thing that is not represented in the sample.

Describe alternatives you've considered
None

Additional context
None

Requester Info
Elizabeth Timmons - NASA/GSFC