Merge doc changes from 3.2 (#8617, #10745).

In the install and library docs, I changed the text to refer to
packaging instead of distutils.  I also checked that the documented
paths correctly reflect what’s really defined in sysconfig; the main
difference with paths defined in distutils.install is that include
directories don’t end with the distribution name anymore (i.e. distutils
uses include/python3.3/spam, sysconfig include/python3.3), I have no
idea why.

Doc/tutorial/interactive.rst

@@ -156,17 +156,18 @@ symbol table.  A command to check (or even suggest) matching parentheses,
 quotes, etc., would also be useful.
 
 One alternative enhanced interactive interpreter that has been around for quite
-some time is `IPython`_, which features tab completion, object exploration and
+some time is IPython_, which features tab completion, object exploration and
 advanced history management.  It can also be thoroughly customized and embedded
 into other applications.  Another similar enhanced interactive environment is
-`bpython`_.
+bpython_.
 
 
 .. rubric:: Footnotes
 
 .. [#] Python will execute the contents of a file identified by the
    :envvar:`PYTHONSTARTUP` environment variable when you start an interactive
-   interpreter.
+   interpreter.  To customize Python even for non-interactive mode, see
+   :ref:`tut-customize`.
 
 
 .. _GNU Readline: http://tiswww.case.edu/php/chet/readline/rltop.html

Doc/tutorial/interpreter.rst

@@ -236,6 +236,29 @@ in the script::
        exec(open(filename).read())
 
 
+.. _tut-customize:
+
+The Customization Modules
+-------------------------
+
+Python provides two hooks to let you customize it: :mod:`sitecustomize` and
+:mod:`usercustomize`.  To see how it works, you need first to find the location
+of your user site-packages directory.  Start Python and run this code:
+
+   >>> import site
+   >>> site.getusersitepackages()
+   '/home/user/.local/lib/python3.2/site-packages'
+
+Now you can create a file named :file:`usercustomize.py` in that directory and
+put anything you want in it.  It will affect every invocation of Python, unless
+it is started with the :option:`-s` option to disable the automatic import.
+
+:mod:`sitecustomize` works in the same way, but is typically created by an
+administrator of the computer in the global site-packages directory, and is
+imported before :mod:`usercustomize`.  See the documentation of the :mod:`site`
+module for more details.
+
+
 .. rubric:: Footnotes
 
 .. [#] On Unix, the Python 3.x interpreter is by default not installed with the
@@ -243,4 +266,3 @@ in the script::
    simultaneously installed Python 2.x executable.
 
 .. [#] A problem with the GNU Readline package may prevent this.
-