plugin.cfg: go gen -> go generate (#3511)
plugin.cfg: go gen -> go generate (#3511)

This takes over #3476 because that is a good change but lacks the DCO
and the author seems unresponsive.

Reformat the file a bit more while we're at it.

Closes: #3476

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