struct: add comment about the if clause

Author: fatih

structs.go

@@ -558,6 +558,7 @@ func (s *Struct) nested(val reflect.Value) interface{} {
 		// TODO(arslan): should this be optional?
 		// do not iterate of non struct types, just pass the value. Ie: []int,
 		// []string, co... We only iterate further if it's a struct.
+		// i.e []foo or []*foo
 		if val.Type().Elem().Kind() != reflect.Struct &&
 			!(val.Type().Elem().Kind() == reflect.Ptr &&
 				val.Type().Elem().Elem().Kind() == reflect.Struct) {