Generate developer documentation with DocFX

[sondreb]

I have a suggestion to generate developer documentation from source code, using DocFX. DocFX is a tool by Microsoft that they used to generate their own system documentation. I have used it on many projects with great success, and it becomes a good reference point when you need to look up and learn more about the available types, methods and more.

DocFX also makes it more clear what parts of the source code could use some attention on XML comments.

https://dotnet.github.io/docfx/

It is fairly easy to setup, but require some additional work on AppVeyor to ensure the publish to github pages is done properly (e.g. e-mail, username and a secret for github publish).

Let me know if this is something you want me to create a PR on, I could supply the base setup and add instructions on AppVeyor secrets that needs to be configured by someone on the team that have proper access.

Here is how it looks, and it have two sections, one is manually written markdown files, the other is generated from the source code: