explicitly declare the scope of runway queries (#15873) (#15880)

tidb-resource-control.md

@@ -262,7 +262,7 @@ SELECT /*+ RESOURCE_GROUP(rg1) */ * FROM t limit 10;
 >
 > This feature is experimental. It is not recommended that you use it in the production environment. This feature might be changed or removed without prior notice. If you find a bug, you can report an [issue](https://github.com/pingcap/tidb/issues) on GitHub.
 
-A runaway query is a query that consumes more time or resources than expected. The term **runaway queries** is used in the following to describe the feature of managing the runaway query.
+A runaway query is a query (`SELECT` statement only) that consumes more time or resources than expected. The term **runaway queries** is used in the following to describe the feature of managing the runaway query.
 
 - Starting from v7.2.0, the resource control feature introduces the management of runaway queries. You can set criteria for a resource group to identify runaway queries and automatically take actions to prevent them from exhausting resources and affecting other queries. You can manage runaway queries for a resource group by including the `QUERY_LIMIT` field in [`CREATE RESOURCE GROUP`](/sql-statements/sql-statement-create-resource-group.md) or [`ALTER RESOURCE GROUP`](/sql-statements/sql-statement-alter-resource-group.md).
 - Starting from v7.3.0, the resource control feature introduces manual management of runaway watches, enabling quick identification of runaway queries for a given SQL statement or Digest. You can execute the statement [`QUERY WATCH`](/sql-statements/sql-statement-query-watch.md) to manually manage the runaway queries watch list in the resource group.