Add DocFX

[Werebunny]

Expected Behavior

Build generates documentation based upon doc comments, and the site documentation site shows them.

Current Behavior

Missing.

Possible Solution

Use DocFXTasks in Nuke. Integrating DocFX into the src project itself creates a lot of crud in the src.

Additional Information

Better documentation for free, since doc comments are done.

[Werebunny]

Encountered issue with Nuke: nuke-build/nuke/issues/323

[Werebunny]

Wait until DocFX v3 is release.