Update error message for idData hexadecimal length (#12582)

Author: hoyosjs

xml/System.Diagnostics/ActivityTraceId.xml

@@ -153,7 +153,7 @@ Because an `ActivityTraceId` is a structure that contains 16 bytes, it can be pa
          ]]></format>
         </remarks>
         <exception cref="T:System.ArgumentOutOfRangeException">
-          <paramref name="idData" /> does not contain 16 hexadecimal characters.
+          <paramref name="idData" /> does not contain 32 hexadecimal characters.
 
 -or-