Fix confusion in runtime_mapping (#90999)

docs/reference/mapping/runtime.asciidoc

@@ -267,8 +267,7 @@ as part of the `runtime_mappings` section, just as you would if
 
 Defining a runtime field in a search request uses the same format as defining
 a runtime field in the index mapping. Just copy the field definition from
-the `runtime_mappings` in the search request to the `runtime` section of the
-index mapping.
+the `runtime_mappings` in the index mapping to the `runtime` section of the search request.
 
 The following search request adds a `day_of_week` field to the
 `runtime_mappings` section. The field values will be calculated dynamically,