Fix bug 575221 referred to dictionary type instead of dict.

Doc/lib/libuserdict.tex

@@ -7,7 +7,7 @@
 \note{This module is available for backward compatibility only.  If
 you are writing code that does not need to work with versions of
 Python earlier than Python 2.2, please consider subclassing directly
-from the built-in \class{dictionary} type.}
+from the built-in \class{dict} type.}
 
 This module defines a class that acts as a wrapper around
 dictionary objects.  It is a useful base class for