This feature is already supported for -a and -A. Let's support it also
when FS specified on command line.
Addresses: https://github.com/systemd/mkosi/pull/721
Signed-off-by: Karel Zak <kzak@redhat.com>
We need to evaluate "include::" directive relatively to project
top-level source directory rather than to the current document
location.
Signed-off-by: Karel Zak <kzak@redhat.com>