[DOC] Add information about classes
It would be helpful to know what each class does and spell out acronyms and abbreviations of the class name so that the function of the class is readily understandable. It seems like most of the information for how to actually use the classes is here for instance https://gitlab.kitware.com/physiology/engine/-/wikis/Creating%20an%20Action, so that's very helpful and covers a lot of what you'd need to add a merge/pull request. However, an exhaustive list of the API entries and what they are used for would be very helpful for extending beyond the boilerplate solutions in the wiki to more advanced use cases.