Sharing this here in case anyone else finds it useful:
https://johnholbrook.github.io/iqcpp-doxygen/
I pointed Doxygen at the C++ header files included with VEXcode IQ, and generated some useful docs with minimal configuration.
The built-in documentation that comes with VEXcode is very good, but if you browse through the included header files you can see that there is some more advanced functionality available that the VEXcode GUI doesn’t show. The doxygen site doesn’t provide all the details that the built-in help does, but it shows everything, and is easier to browse than the raw header files.