CHANGELOG: add data dir permission breaking changes doc
CHANGELOG: add data dir permission breaking changes doc

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