[2.7] bpo-33280: Reorganize external Tcl/Tk references. (GH-6473). (GH-6607)

(cherry picked from commit 67a8f4f)

Co-authored-by: Andrés Delfino <34587441+andresdelfino@users.noreply.github.com>

Author: andresdelfino

Doc/library/tkinter.rst

@@ -11,6 +11,11 @@ the Tk GUI toolkit.  Both Tk and :mod:`Tkinter` are available on most Unix
 platforms, as well as on Windows systems.  (Tk itself is not part of Python; it
 is maintained at ActiveState.)
 
+Running ``python -m Tkinter`` from the command line should open a window
+demonstrating a simple Tk interface, letting you know that :mod:`Tkinter` is
+properly installed on your system, and also showing what version of Tcl/Tk is
+installed, so you can read the Tcl/Tk documentation specific to that version.
+
 .. note::
 
    :mod:`Tkinter` has been renamed to :mod:`tkinter` in Python 3.  The
@@ -19,6 +24,8 @@ is maintained at ActiveState.)
 
 .. seealso::
 
+   Tkinter documentation:
+
    `Python Tkinter Resources <https://wiki.python.org/moin/TkInter>`_
       The Python Tkinter Topic Guide provides a great deal of information on using Tk
       from Python and links to other sources of information on Tk.
@@ -32,17 +39,32 @@ is maintained at ActiveState.)
    `Tkinter docs from effbot <http://effbot.org/tkinterbook/>`_
       Online reference for tkinter supported by effbot.org.
 
-   `Tcl/Tk manual <https://www.tcl.tk/man/tcl8.5/>`_
-      Official manual for the latest tcl/tk version.
-
-   `Programming Python <http://learning-python.com/books/about-pp4e.html>`_
+   `Programming Python <http://learning-python.com/about-pp4e.html>`_
       Book by Mark Lutz, has excellent coverage of Tkinter.
 
-   `Modern Tkinter for Busy Python Developers <http://www.amazon.com/Modern-Tkinter-Python-Developers-ebook/dp/B0071QDNLO/>`_
+   `Modern Tkinter for Busy Python Developers <https://www.amazon.com/Modern-Tkinter-Python-Developers-ebook/dp/B0071QDNLO/>`_
       Book by Mark Rozerman about building attractive and modern graphical user interfaces with Python and Tkinter.
 
    `Python and Tkinter Programming <https://www.manning.com/books/python-and-tkinter-programming>`_
-      The book by John Grayson (ISBN 1-884777-81-3).
+      Book by John Grayson (ISBN 1-884777-81-3).
+
+   Tcl/Tk documentation:
+
+   `Tk commands <https://www.tcl.tk/man/tcl8.6/TkCmd/contents.htm>`_
+      Most commands are available as :mod:`Tkinter` or :mod:`Tkinter.ttk` classes.
+      Change '8.6' to match the version of your Tcl/Tk installation.
+
+   `Tcl/Tk recent man pages <https://www.tcl.tk/doc/>`_
+      Recent Tcl/Tk manuals on www.tcl.tk.
+
+   `ActiveState Tcl Home Page <http://tcl.activestate.com/>`_
+      The Tk/Tcl development is largely taking place at ActiveState.
+
+   `Tcl and the Tk Toolkit <https://www.amazon.com/exec/obidos/ASIN/020163337X>`_
+      Book by John Ousterhout, the inventor of Tcl.
+
+   `Practical Programming in Tcl and Tk <http://www.beedub.com/book/>`_
+      Brent Welch's encyclopedic book.
 
 
 Tkinter Modules
@@ -182,18 +204,6 @@ documentation that exists. Here are some hints:
   when nothing else makes sense.
 
 
-.. seealso::
-
-   `ActiveState Tcl Home Page <http://tcl.activestate.com/>`_
-      The Tk/Tcl development is largely taking place at ActiveState.
-
-   `Tcl and the Tk Toolkit <http://www.amazon.com/exec/obidos/ASIN/020163337X>`_
-      The book by John Ousterhout, the inventor of Tcl.
-
-   `Practical Programming in Tcl and Tk <http://www.beedub.com/book/>`_
-      Brent Welch's encyclopedic book.
-
-
 A Simple Hello World Program
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^