What does this MR do?

Rename all groups.dox files to modules.dox. In the code, Doxygen calls it "groups", but in the final documentation it is called "modules". I think "modules" is a more meaningful name for a file in the code directories.

Is there something that needs to be double checked?

No

Can this MR be accepted?

• @sospinar approves
• Pipeline passing

Related issues

None