Complete the API documentation

[Armavica]

Hi, as part of the review that I am doing for JOSS openjournals/joss-reviews#10580 I have to evaluate the following point:

Functionality documentation: Is the core functionality of the software documented to a satisfactory level (e.g., API method documentation)?

I saw that most of the modules and functions are documented, which is great, but several are not, which seem to be core functionality, like the optimize module and submodules, and most of the macros, including the analytical!, ode! and sde! macros which are mentioned in the README as main entrypoints for users of the library.

So, it would seem useful to write complete documentation for these items.