contrib/mixin/mixin.libsonnet: Unify alerting description
contrib/mixin/mixin.libsonnet: Unify alerting description

rnaveiras/etcd,gyuho/etcd,mqliang/etcd,mqliang/etcd,etcd-io/etcd,ajityagaty/etcd,mqliang/etcd,rnaveiras/etcd,etcd-io/etcd,mkumatag/etcd,coreos/etcd,gyuho/etcd,mkumatag/etcd,ajityagaty/etcd,coreos/etcd,rnaveiras/etcd,mkumatag/etcd,etcd-io/etcd,ajityagaty/etcd