Fixed double hyphens that are rendered to literal en-dashes in the documenation.
diff --git a/Doc/tutorial/stdlib2.rst b/Doc/tutorial/stdlib2.rst
index 50b74d1..2d11d55 100644
--- a/Doc/tutorial/stdlib2.rst
+++ b/Doc/tutorial/stdlib2.rst
@@ -1,8 +1,8 @@
.. _tut-brieftourtwo:
*********************************************
-Brief Tour of the Standard Library -- Part II
-*********************************************
+Brief Tour of the Standard Library --- Part II
+**********************************************
This second tour covers more advanced modules that support professional
programming needs. These modules rarely occur in small scripts.