Extract documentation to HTML

[tsahi]

Is your feature request related to a problem? Please describe.
The code contains API documentation. We should extract this documentation to HTML and post it on a web site, such as on github.io.

Describe the solution you'd like
To alternatives I know of:

1. Doxygen
2. Sandcastle

Both can produce decent HTML, but Doxygen is much faster, because it extracts the text from the source, while Sandcastle reflects on the binaries.

Describe alternatives you've considered
The API documentation of the latest release is available at https://docs.microsoft.com/en-us/previous-versions/msp-n-p/dn170426(v=pandp.60), but as we add new functionality, we will need to have an updated version.