Update the string limit in the faulthandler documentations

Doc/library/faulthandler.rst

@@ -23,7 +23,7 @@ tracebacks:
 
 * Only ASCII is supported. The ``backslashreplace`` error handler is used on
   encoding.
-* Each string is limited to 100 characters.
+* Each string is limited to 500 characters.
 * Only the filename, the function name and the line number are
   displayed. (no source code)
 * It is limited to 100 frames and 100 threads.