NEWS: mention CVE-2020-25637 in v6.8.0 release notes
NEWS: mention CVE-2020-25637 in v6.8.0 release notes

Signed-off-by: Mauro Matteo Cascella <a54060f20381b48a62b591e599d9448f6ef76a30@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

jfehlig/libvirt,zippy2/libvirt,crobinso/libvirt,crobinso/libvirt,olafhering/libvirt,olafhering/libvirt,crobinso/libvirt,libvirt/libvirt,jardasgit/libvirt,jardasgit/libvirt,jardasgit/libvirt,zippy2/libvirt,jardasgit/libvirt,nertpinx/libvirt,nertpinx/libvirt,jfehlig/libvirt,libvirt/libvirt,crobinso/libvirt,jardasgit/libvirt,zippy2/libvirt,libvirt/libvirt,olafhering/libvirt,olafhering/libvirt,jfehlig/libvirt,zippy2/libvirt,jfehlig/libvirt,libvirt/libvirt,nertpinx/libvirt,nertpinx/libvirt,nertpinx/libvirt