Describe supported OSes
BIND has this very nice PLATFORMS.md file. We have part of that information available in the ARM, but it's fragmented and incomplete.
create page on wiki (or in kea sources) This should be easily modifiable by everyone involved (devs, qa, Vicky)
move the information from ARM there (and have pointer in ARM)
add a section about the systems we actually test on
having the same approach as bind (supported/mostly supported/known to be broken) is a very good model