[doc]: Add a project-setup doc in new tutorial series for beginners

[rossmc]

Describe the request
As discussed with @jcalcaben on slack, I'm proposing to add a number of tutorial to help beginners get started with PWA Studio.

Possible solutions
Describe in for beginners how to use @magento/pwa command to setup a new PWA studio project.

Screenshots
If applicable, add screenshots to help explain the problem.

Please let us know whether this is a new topic or a topic change request:

• New Topic Request (ie. missing entire topic/section)
• Topic Change Request (ie. spelling, organization)