bpo-21302: Update time.sleep() doc for clock_nanosleep() (GH-28311)

Clean-up also What's New in Python 3.11 doc: move entries to the
correct sections.

Author: vstinner

Doc/library/time.rst

@@ -362,6 +362,11 @@ Functions
       by a signal, except if the signal handler raises an exception (see
       :pep:`475` for the rationale).
 
+   .. versionchanged:: 3.11
+      In Unix operating systems, the ``clock_nanosleep()`` function is now
+      used, if available: it allows to sleep for an interval specified with
+      nanosecond precision.
+
 
 .. index::
    single: % (percent); datetime format

Doc/whatsnew/3.11.rst

@@ -66,7 +66,6 @@ Summary -- Release highlights
 .. PEP-sized items next.
 
 
-
 New Features
 ============
 
@@ -209,8 +208,8 @@ math
 os
 --
 
-* On Windows, :func:`os.urandom` uses ``BCryptGenRandom()`` instead of ``CryptGenRandom()``
-  which is deprecated.
+* On Windows, :func:`os.urandom` now uses ``BCryptGenRandom()``,
+  instead of ``CryptGenRandom()`` which is deprecated.
   (Contributed by Dong-hee Na in :issue:`44611`.)
 
 
@@ -232,6 +231,14 @@ sqlite3
   (Contributed by Aviv Palivoda, Daniel Shahaf, and Erlend E. Aasland in
   :issue:`16379`.)
 
+time
+----
+
+* In Unix operating systems, :func:`time.sleep` now uses the
+  ``clock_nanosleep()`` function, if available, which allows to sleep for an
+  interval specified with nanosecond precision.
+  (Contributed by Livius and Victor Stinner in :issue:`21302`.)
+
 
 Removed
 =======
@@ -265,6 +272,18 @@ Removed
   and :class:`fileinput.FileInput`, deprecated since Python 3.9.
   (Contributed by Hugo van Kemenade in :issue:`45132`.)
 
+* The following deprecated functions and methods are removed in the :mod:`gettext`
+  module: :func:`~gettext.lgettext`, :func:`~gettext.ldgettext`,
+  :func:`~gettext.lngettext` and :func:`~gettext.ldngettext`.
+
+  Function :func:`~gettext.bind_textdomain_codeset`, methods
+  :meth:`~gettext.NullTranslations.output_charset` and
+  :meth:`~gettext.NullTranslations.set_output_charset`, and the *codeset*
+  parameter of functions :func:`~gettext.translation` and
+  :func:`~gettext.install` are also removed, since they are only used for
+  the ``l*gettext()`` functions.
+  (Contributed by Dong-hee Na and Serhiy Storchaka in :issue:`44235`.)
+
 
 Optimizations
 =============
@@ -317,6 +336,10 @@ Deprecated
   It is untested and undocumented and also not used by webbrowser itself.
   (Contributed by Dong-hee Na in :issue:`42255`.)
 
+* The behavior of returning a value from a :class:`~unittest.TestCase` and
+  :class:`~unittest.IsolatedAsyncioTestCase` test methods (other than the
+  default ``None`` value), is now deprecated.
+
 
 Removed
 =======
@@ -334,6 +357,7 @@ Removed
 * Remove the deprecated ``split()`` method of :class:`_tkinter.TkappType`.
   (Contributed by Erlend E. Aasland in :issue:`38371`.)
 
+
 Porting to Python 3.11
 ======================
 
@@ -476,19 +500,3 @@ Removed
   Use the new :c:type:`PyConfig` API of the :ref:`Python Initialization Configuration
   <init-config>` instead (:pep:`587`).
   (Contributed by Victor Stinner in :issue:`44113`.)
-
-* The following deprecated functions and methods are removed in the :mod:`gettext`
-  module: :func:`~gettext.lgettext`, :func:`~gettext.ldgettext`,
-  :func:`~gettext.lngettext` and :func:`~gettext.ldngettext`.
-
-  Function :func:`~gettext.bind_textdomain_codeset`, methods
-  :meth:`~gettext.NullTranslations.output_charset` and
-  :meth:`~gettext.NullTranslations.set_output_charset`, and the *codeset*
-  parameter of functions :func:`~gettext.translation` and
-  :func:`~gettext.install` are also removed, since they are only used for
-  the ``l*gettext()`` functions.
-  (Contributed by Dong-hee Na and Serhiy Storchaka in :issue:`44235`.)
-
-* The behavior of returning a value from a :class:`~unittest.TestCase` and
-  :class:`~unittest.IsolatedAsyncioTestCase` test methods (other than the default ``None``
-  value), is now deprecated.