Target Docusaurus format

[gsferreira]

Hi,

I know that I should have opened an Issue first, but since I've found the following issues that are related and are non-answered, I tried to come up with something that would solve my problem.

• Create plugin architecture for output formats #77
• Alternative file structure #76
• Support folders for serving content #79

I want to generate the Markdown files in a folder structure that makes sense on a Docusaurus docs website.
That means some conventions from Jekyll need to be overridden with different rules.
I've found 2:

1. Files should be organized in a folder tree following the namespaces.
2. Types should be in the same folder as the methods/properties.

On this PR I add a flag type-folders to address the second point.

And I've built a new console project, that can be delivered as a dotnet tool, that plugs the Docusaurus file path rules into the generator.

Let me know if this is useful. It's solving my problem at the moment.
I'm happy to fine-tune it based on your feedback.