CHANGELOG: add learner metrics
CHANGELOG: add learner metrics

dannysauer/etcd,mkumatag/etcd,dannysauer/etcd,cockroachdb/etcd,coreos/etcd,cockroachdb/etcd,coreos/etcd,gyuho/etcd,rnaveiras/etcd,mqliang/etcd,mkumatag/etcd,mqliang/etcd,rnaveiras/etcd,ajityagaty/etcd,mqliang/etcd,rnaveiras/etcd,etcd-io/etcd,gyuho/etcd,li-ang/etcd,mkumatag/etcd,li-ang/etcd,etcd-io/etcd,ajityagaty/etcd,ajityagaty/etcd,etcd-io/etcd