Documentation for v4

All of the documentation, READMEs, etc. for this directory are now stored in the doc/raddb directory, which is a soft link to the Asciidoc source. Those files are converted to HTML by Antora.

If the server is being built from source, you can build the HTML documentation and see if via the following commands:

make docsite
ls build/docsite/freeradius-server/latest/index.html

If the server is pre-packaged, then the HTML documentation should be available as a separate package.