Remove comment about -X and string exceptions. Error noted by

freddrake · freddrake · commit 88c023b8639e · 2000-09-07T16:33:32.000Z
Justin D. Pettit &lt;jpettit@raznick.com&gt;.
diff --git a/Doc/lib/libexcs.tex b/Doc/lib/libexcs.tex
@@ -106,11 +106,10 @@ \section{Built-in Exceptions}
 \member{args} contains the verbatim constructor arguments as a tuple.
 \end{excdesc}
 
+
 \setindexsubitem{(built-in exception)}
 
 The following exceptions are the exceptions that are actually raised.
-They are class objects, except when the \programopt{-X} option is used
-to revert back to string-based standard exceptions.
 
 \begin{excdesc}{AssertionError}
 \stindex{assert}
