Doc generator

[Gijsreyn]

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This pull request addresses an initial setup to start generating documentation for all classes. The end goal of the doc generator:

• Ability to generate all documentation files on the fly in a standardized format
• Should validate if modules have been modified, the documentation files are also always up to date

[!NOTE]
The static methods came from the idea on the DSC discussion by Mikey. This is far from crystalized, but an attempt to kickstart the idea for resource authors in this repository. I talked with Jim Truher also on class documentation, but there isn't anything available (yet). In the current commit, you can also see the attempt to dynamically generate docs using the Microsoft.PowerShell.PlatyPS module. However, there are to many properties outputted when converting for Markdown. That's why I choose the way to build it up using separate functions.

Microsoft Reviewers: Open in CodeFlow

[Gijsreyn]

@denelon Curious to your thoughts.

[denelon]

I'd like @ryfu-msft to take a look. I think the idea is sound, I just want to make sure we're not departing too far away from making it easy to add new resources and subsequently have the ability to move them to their own new "home". For the Microsoft modules they might stay here or move to another repository, and for the non-Microsoft resources, we might want them to move to either the DSC Community or to live with the product they configure.