Extend examples and Guidance for usage of Clocks

[chrbertsch]

.. now that they are more and more used.

See comments from the FMI Design Meeting in Munich Dec 2025: https://github.com/modelica/fmi-design/blob/master/Meetings/2024/2024-12-02-05-FMI-Design-Munich-ASAM/README.md#minutes:
"Give examples for call sequences with clocks e.g. in the implementers' guide (ToDo: Collect questions, create examples? Describe in the guide? Concentrate on clocks for FMI 3.0.3)"

One example is available at https://github.com/clagms/synchronous-clock-fmus

[chrbertsch]

FMI-Design-Webmeeting:

• E.g. Calling sequences for connected FMUs (similar to the collection of initialization examples for ME FMUs for FMI 2.0)
• Claudios example could be extended for different kind of clocks.
• @masoud-najafi : I have examples that I could share!
• Klaus: That would be great!

Repo: https://github.com/modelica/fmi-clocks-sandbox/