The Debian maintainer informed me that there isn't such a config
file in the
upstream source code and I think it would be helpful if the directory with the
correct permissions and the config file, which could f.e. only contain a
commented reference to the iwd.config man page, would be created OOTB.
I added a sample doc/main.conf in commit:
04fccea63bd4 ("doc: Add sample main.conf file"). We used to have something
similar, but it was removed by commit:
e915156be1c6 ("doc: Remove obsolete main.conf example file")
The sample covers main.conf options that should be most relevant towards the use
case you describe. If I missed some, we can add them as needed. Let us know if
this is what the Debian package maintainer had in mind.