* Add 1.6.0 release notes

Preliminary notes for the 1.6.0 release
Signed-off-by: Miek Gieben <miek@miek.nl>

* Update notes/coredns-1.6.0.md
Co-Authored-By: Michael Grosser <development@stp-ip.net>

* Update notes/coredns-1.6.0.md
Co-Authored-By: Michael Grosser <development@stp-ip.net>