make it obvious that the last project meta repository path is recursive

[JanZerebecki]

Is your feature request related to a problem? Please describe.
I didn't notice that only the last project meta repository path is recursive. Wondered for too long why it doesn't work as expected.

Describe the solution you'd like
Add an attribute recursive with value true or false to make it obvious. Add it on store or view to still accept the format without the attribute. If that is preferable reject if it is set to true on anything but the last path.

Describe alternatives you've considered
Only note this in documentation.

Additional context
openSUSE/obs-docu#159

[igh-fp]

Same for us. We had a problem with the Leap 15.5 repo and all we had to do was to remove the standard repository at the last position.