[3.10] [doc] Link to deprecation policy PEP from the DeprecationWarning documentation (GH-28123) (#28126)

ambv · web-flow · commit 2184bc7fe15f · 2021-09-02T18:18:47.000+02:00
(cherry picked from commit a7ef15a) Co-authored-by: Łukasz Langa <lukasz@langa.pl>
diff --git a/Doc/library/exceptions.rst b/Doc/library/exceptions.rst
@@ -748,6 +748,8 @@ The following exceptions are used as warning categories; see the
    (:pep:`565`). Enabling the :ref:`Python Development Mode <devmode>` shows
    this warning.
 
+   The deprecation policy is described in :pep:`387`.
+
 
 .. exception:: PendingDeprecationWarning
 
@@ -762,6 +764,8 @@ The following exceptions are used as warning categories; see the
    Ignored by the default warning filters. Enabling the :ref:`Python
    Development Mode <devmode>` shows this warning.
 
+   The deprecation policy is described in :pep:`387`.
+
 
 .. exception:: SyntaxWarning
 
