There are several items I think could have a bit more documentation:

Need an overview on how unit files relate to each other

It took me some time to figure out the relationship between test, scenario, jig, and interface/trigger files.
Would be good to have some documentation on how they relate to each other.

No definition for CFTI

There was no explanation on what CFTI is, which is a bit confusing.
"Common Factory Test Interface" was only mentioned on xobs/jig-20-interface-https/README.md

Explanation on working directory

At the moment working directory can be specified in multiple places:

• .test files
• .scenario files
• .trigger files
• .interface files

They are also related to DefaultWorkingDirectory which can also be specified in different places:

• .jig files
• command line (jig-20 only)

Are they completely independent from each other?
E.g. the Working Directory in one file only applies to commands within that onefile?