Update nested-query.asciidoc

Changed score_mode `total` to `sum` to be consistent with parent-child etc

docs/reference/query-dsl/queries/nested-query.asciidoc

@@ -52,7 +52,7 @@ fields referenced inside the query must use the complete path (fully
 qualified).
 
 The `score_mode` allows to set how inner children matching affects
-scoring of parent. It defaults to `avg`, but can be `total`, `max` and
+scoring of parent. It defaults to `avg`, but can be `sum`, `max` and
 `none`.
 
 Multi level nesting is automatically supported, and detected, resulting