As requested by @myoungwoon in D7126#123769, study the possibility to use [DocFx](https://dotnet.github.io/docfx) to generate the C# API docs as it is being done for Tizen.
The output of this task should be a list of pros and cons to further discuss the move.
- [X] Filter out unwanted API (legacy, ...)
- [ ] Check that cross referencing works (links to other APIs, methods, ...)
- [ ] Display only useful info (remove long inheritance trees, protected methods, ...)
- [ ] Use the site's theme
- [X] Add tutorials and programming guides