Readme: mention update, delete, subselect (#111)

Author: janedbal

README.md

@@ -96,6 +96,8 @@ JOIN account a2_ ON (...)
 ```
 
 ### Advanced usage notes
+- Even `UPDATE` and `DELETE` queries are supported
+- Subselects are also supported
 - It works even for tables that are not present in the DQL, but are present in SQL!
     - For example parent table from [class table inheritance](https://www.doctrine-project.org/projects/doctrine-orm/en/2.9/reference/inheritance-mapping.html#class-table-inheritance) when selecting children
 - Any invalid usage is checked in runtime