Update OMPython documentation to 4.0.0 in the User's guide

[casella]

Lots of improvements were done to OMPython 4.0.0, with some breaking changes.

The documentation of OMPython is shown in the User Guide here.

The source code for that is stored in https://github.com/OpenModelica/OpenModelica/blob/master/doc/UsersGuide/source/ompython.rst

@syntron would you be so kind to update it according to all your changes? Please do a PR on that file, so @adeas31 can review it.

Thanks!

[syntron]

@casella: I will have a look and work on an update; thanks for the hint there to find the source data ;-) I checked the web page and did not find the reference ...

[syntron]

working on it - see OpenModelica/OpenModelica#14639

[syntron]

I found the repository of @pyotel at https://github.com/pyotel/OMPython - this includes a quite good updated guid for OMPython (README.md and CLAUDE.md)