Fixed a typo in ReST markup.
diff --git a/Doc/library/turtle.rst b/Doc/library/turtle.rst
index d96a543..efe9ae7 100644
--- a/Doc/library/turtle.rst
+++ b/Doc/library/turtle.rst
@@ -2271,9 +2271,8 @@
 
    python -m turtledemo
 
-Alternatively, you can run the demo scripts individually.  For example,
+Alternatively, you can run the demo scripts individually.  For example, ::
 
-::
    python -m turtledemo.bytedesign
 
 The :mod:`turtledemo` package directory contains: