We should document PowerShell-IoT module

[SteveL-MSFT]

Documentation Issue

This is published on the gallery and repo is here:
https://github.com/powershell/powershell-iot

Context of the issue

• URL to the article (Docs or GitHub URL):

• Issue affects the following content (check all that apply):

  Cmdlet reference & about_ topics

  • Version 7.x preview content
  • Version 7.0 content
  • Version 6 content
  • Version 5.1 content

  Conceptual articles

  • Fundamental conceptual articles
  • Script sample articles
  • DSC articles
  • Gallery articles
  • JEA articles
  • WMF articles
  • SDK articles

• Is the issue specific to a platform (Y/N - Win/macOS/Linux):

Detailed description of the issue

cc @anmenaga

[sdwheeler]

@SteveL-MSFT Is this planned to ship in 7.1? If not then we should ship the MAML in the Gallery package.