Model adaptivity configuration docs: Clarify micro_file_names

[MakisH]

Looking first at the micro_file_names configuration option, I was confused on whether the order plays any role, since this is a list (not a dictionary). I understand that this is always supposed to be in the order of decreasing model fidelity, considering the return values of the switching_function at the bottom of https://precice.org/tooling-micro-manager-model-adaptivity.html

Also: is fidelity meant as a synonym for resolution here? Because the switching_function seems to take a resolution argument.

Checklist:

• I made sure that the CI passed before I ask for a review.
• If necessary, I made changes to the documentation and/or added new content.