Clarify who maintains Tkinter and who maintains Tk.

Doc/lib/tkinter.tex

@@ -38,9 +38,10 @@ Python.
 \moduleauthor{Guido van Rossum}{guido@Python.org}
 
 The \module{Tkinter} module (``Tk interface'') is the standard Python
-interface to the Tk GUI toolkit, now maintained at ActiveState.  Both
-Tk and \module{Tkinter} are available on most \UNIX{} platforms, as well
-as on Windows and Macintosh systems.
+interface to the Tk GUI toolkit.  Both Tk and \module{Tkinter} are
+available on most \UNIX{} platforms, as well as on Windows and
+Macintosh systems.  (Tk itself is not part of Python; it is maintained
+at ActiveState.)
 
 \begin{seealso}
 \seetitle[http://www.python.org/topics/tkinter/]