Update AuthenticatedStream.xml (#7800)

In the Remarks for 'LeaveInnerStreamOpen Property', I believe the author meant 'underlying transport stream', not 'underlined transport stream'.

Author: Nicholas Piazza

xml/System.Net.Security/AuthenticatedStream.xml

@@ -588,7 +588,7 @@ The following example demonstrates displaying the value of this property.
           <format type="text/markdown"><![CDATA[  
   
 ## Remarks  
- When set to `true`, the stream passed to the constructor of this class will not be closed after the instance of this class is closed. When set to `false`, closing the instance of this class will also close the underlined transport stream. The default value of this property is `false`.  
+ When set to `true`, the stream passed to the constructor of this class will not be closed after the instance of this class is closed. When set to `false`, closing the instance of this class will also close the underlying transport stream. The default value of this property is `false`.  
   
  ]]></format>
         </remarks>