Spelling fix.

pkg/cluster/cluster.go

@@ -377,7 +377,7 @@ func (c *Cluster) compareStatefulSetWith(statefulSet *v1beta1.StatefulSet) *comp
 	}
 	if !reflect.DeepEqual(container1.EnvFrom, container2.EnvFrom) {
 		needsRollUpdate = true
-		reasons = append(reasons, "new statefulset's container environment sources doesn't match the current one")
+		reasons = append(reasons, "new statefulset's container environment sources don't match the current one")
 	}
 
 	if needsRollUpdate || needsReplace {