Capitalize "Python" for consistency.

Describe UserDict and UserList individually so they aren't too hideous in
the presentation.

Doc/lib/libpython.tex

@@ -14,11 +14,13 @@ environment.  Here's an overview:
 --- Names for all built-in types.
 
 \item[UserDict]
+--- Class wrapper for dictionary objects.
+
 \item[UserList]
---- Class wrappers for dictionary and list objects.
+--- Class wrapper for list objects.
 
 \item[operator]
---- All python's standard operators as built-in functions.
+--- All Python's standard operators as built-in functions.
 
 \item[traceback]
 --- Print or retrieve a stack traceback.

Doc/libpython.tex

@@ -14,11 +14,13 @@ environment.  Here's an overview:
 --- Names for all built-in types.
 
 \item[UserDict]
+--- Class wrapper for dictionary objects.
+
 \item[UserList]
---- Class wrappers for dictionary and list objects.
+--- Class wrapper for list objects.
 
 \item[operator]
---- All python's standard operators as built-in functions.
+--- All Python's standard operators as built-in functions.
 
 \item[traceback]
 --- Print or retrieve a stack traceback.