Update jdbc.md

docs/en/operations/table_engines/jdbc.md

@@ -10,6 +10,9 @@ This engine supports the [Nullable](../../data_types/nullable.md) data type.
 
 ```sql
 CREATE TABLE [IF NOT EXISTS] [db.]table_name
+(
+    columns list...
+)
 ENGINE = JDBC(dbms_uri, external_database, external_table)
 ```