While we have a wiki page describing the feature [1] since the
feature is distributed in our .tar.gz we ought to document it. So
I went ahead, copied the wiki page and reformatted so it fits our
docs coding style.
1: http://wiki.libvirt.org/page/NSS_module
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
