notes: more PR and clarify backwards incompat changes (#4185)
notes: more PR and clarify backwards incompat changes (#4185)

A new PR and author. Also clarify the impact of the backwards
incompatible changes are minimal for most users.

Signed-off-by: Miek Gieben <00b357f94cf3a1145a32703fb42e2d80418ab806@miek.nl>
miekg/coredns,yongtang/coredns,chrisohaver/coredns,miekg/coredns,johnbelamaric/coredns,johnbelamaric/coredns,coredns/coredns