Do not touch sys.path when site is imported and python was started with -S.

Original patch by Carl Meyer, review by Brett Cannon, small doc editions by
yours truly.  Fixes #11591.
diff --git a/Doc/whatsnew/3.3.rst b/Doc/whatsnew/3.3.rst
index d86826c..7f05a84 100644
--- a/Doc/whatsnew/3.3.rst
+++ b/Doc/whatsnew/3.3.rst
@@ -128,3 +128,8 @@
 
 * Stub
 
+
+.. Issue #11591: When :program:`python` was started with :option:`-S`,
+   ``import site`` will not add site-specific paths to the module search
+   paths.  In previous versions, it did.  See changeset for doc changes in
+   various files.  Contributed by Carl Meyer with editions by Éric Araujo.