You're reading the documentation for the non-stable development version of MoveIt 2. For the stable, released version, please have a look at Humble.
How To Generate API Doxygen Reference Locally
Run doxygen in the root of the moveit2 repository.
sudo apt-get install doxygen graphviz
Navigate to the moveit2 repository:
Run reference generation command with desired output directory path:
The documentation entrypoint in a browser is index.html which you can access with: