Fix incorrect exception type in DataTableReader.GetOrdinal documentation (#11461)

Author: Copilot

xml/System.Data/DataTableReader.xml

@@ -1498,7 +1498,7 @@ Russ
 ## Remarks  
  Because most of the methods provided by the <xref:System.Data.DataTableReader> class must be provided with an ordinal column number, you can use the `GetOrdinal` method to retrieve the column number, given the name of the column.  
   
- `GetOrdinal` performs a case-sensitive lookup first. If it fails, a second case-insensitive search is made. If the column number is not found an `IndexOutOfRangeException` is thrown.  
+ `GetOrdinal` performs a case-sensitive lookup first. If it fails, a second case-insensitive search is made. If the column number is not found an `ArgumentException` is thrown.  
   
  `GetOrdinal` is kana-width insensitive.