Never mind... I finally got AI to teach me how to generate it. I sure lost some hair in the process, though. Here is what I did. Happy are those who already knew how to generate documentation.
Download source for Doxygen (1.12.0 at the time of posting)
Build with CMake. Oh, wait... your version of "bison" isn't good enough for Doxygen? Download bison 2.7. (On Mac I used the Terminal command `brew install bison@2.7`). What, CMake still thinks your version of "bison" isn't good enough? Click on CMake's "Environment" button (GUI CMake), and where you see PATH, enter the full path to where bison 2.7 is located, and then a colon, BEFORE the paths that are currently typed there. If you used `brew install`, this path is likely to be something like `/opt/homebrew/Cellar/bison@2.7/2.7.1_1/bin`.
Now CMake should configure correctly and generate a Makefile.
In Terminal navigate to the Doxygen/build folder and enter `make`.
If you want you can install the `doxygen` binary somewhere in your PATH like /usr/local/bin. Or you can use it right where it sits and include its full path to invoke it.
You should have the source code download for SFML.Net. In Terminal, navigate to the `src` folder within that folder. Once there, enter:
`/path/to/doxygen -g Doxyfile.sfml.net`
Then open that file with a text editor. The AI recommended that I fill out the following fields: there may be more that you'll want, but this should at least give you something. The default generated Doxyfile is large, so just use the Find command to look for these keywords:
PROJECT_NAME = "SFML.Net"
PROJECT_BRIEF = "Simple and Fast Multimedia Library for .NET"
INPUT = /path/to/sfml.net/source/code (if the Doxyfile is located in .../SFML.Net.x.x.x/src/ this can be blank)
FILE_PATTERNS = *.cs
RECURSIVE = YES
OUTPUT_DIRECTORY = ./docs
GENERATE_HTML = YES
HTML_OUTPUT = html
EXTRACT_ALL = YES
EXTRACT_PRIVATE = YES
EXTRACT_PACKAGE = YES
EXTRACT_STATIC = YES
GENERATE_LATEX = NO
HAVE_DOT = NO
Save and close the Doxyfile.
In Terminal type:
`/path/to/doxygen Doxyfile.sfml.net`
There should now be a "docs" folder located within "src". Go inside "docs", make an alias/symlink of "index.html", and put that alias somewhere easy to access.
You've finally got C# SFML Docs, and a lot less hair.