MAINTAINERS: remove deprecated CoreOS email, update other maintainers
MAINTAINERS: remove deprecated CoreOS email, update other maintainers

With latest email addresses.

CoreOS emails are being deprecated in a few weeks.

Signed-off-by: Gyuho Lee <3454051ee3341eb69bdf6fca40899cdad4d86496@gmail.com>

ajityagaty/etcd,li-ang/etcd,mkumatag/etcd,bdarnell/etcd,mqliang/etcd,sinsharat/etcd,rnaveiras/etcd,cockroachdb/etcd,mkumatag/etcd,sebrandon1/etcd,cockroachdb/etcd,joshix/etcd,gyuho/etcd,joshix/etcd,sinsharat/etcd,glevand/coreos--etcd,vimalk78/etcd,gyuho/etcd,ajityagaty/etcd,fanminshi/etcd,xiang90/etcd,dannysauer/etcd,mkumatag/etcd,mqliang/etcd,xiang90/etcd,coreos/etcd,rnaveiras/etcd,lorneli/etcd,bdarnell/etcd,rnaveiras/etcd,glevand/coreos--etcd,li-ang/etcd,mqliang/etcd,coreos/etcd,dannysauer/etcd,etcd-io/etcd,vimalk78/etcd,sebrandon1/etcd,ajityagaty/etcd,lorneli/etcd,etcd-io/etcd,fanminshi/etcd,etcd-io/etcd