docs: add changelog and upgrading guide

Author: kenjis

user_guide_src/source/changelogs/v4.4.0.rst

@@ -47,6 +47,11 @@ Method Signature Changes
   ``RouteCollection::__construct()``.
 - **Validation:** The method signature of ``Validation::check()`` has been changed.
   The ``string`` typehint on the ``$rule`` parameter was removed.
+- **Session:** The second parameter of ``Session::__construct()`` has been
+  changed from ``Config\App`` to ``Config\Session``.
+- **Session:** The first parameter of ``__construct()`` in ``BaseHandler``,
+  ``DatabaseHandler``, ``FileHandler``, ``MemcachedHandler``, and ``RedisHandler``
+  has been changed from ``Config\App`` to ``Config\Session``.
 
 Enhancements
 ************
@@ -120,6 +125,7 @@ Changes
 *******
 
 - **Config:** The deprecated Cookie items in **app/Config/App.php** has been removed.
+- **Config:** The deprecated Session items in **app/Config/App.php** has been removed.
 - **Config:** Routing settings have been moved to **app/Config/Routing.php** config file.
   See :ref:`Upgrading Guide <upgrade-440-config-routing>`.
 - **DownloadResponse:** When generating response headers, does not replace the ``Content-Disposition`` header if it was previously specified.
@@ -138,6 +144,10 @@ Deprecations
   are deprecated. Because these methods have been moved to ``BaseExceptionHandler`` or
   ``ExceptionHandler``.
 - **Autoloader:** ``Autoloader::sanitizeFilename()`` is deprecated.
+- **Session:** The property ``$sessionDriverName``, ``$sessionCookieName``,
+  ``$sessionExpiration``, ``$sessionSavePath``, ``$sessionMatchIP``,
+  ``$sessionTimeToUpdate``, and ``$sessionRegenerateDestroy`` in ``Session`` are
+  deprecated, and no longer used. Use ``$config`` instead.
 
 Bugs Fixed
 **********

user_guide_src/source/installation/upgrade_440.rst

@@ -100,6 +100,16 @@ The Cookie config items in **app/Config/App.php** are no longer used.
 2. Remove the properties (from ``$cookiePrefix`` to ``$cookieSameSite``) in
    **app/Config/App.php**.
 
+app/Config/Session.php
+----------------------
+
+The Session config items in **app/Config/App.php** are no longer used.
+
+1. Copy **app/Config/Session.php** from the new framework to your **app/Config**
+   directory, and configure it.
+2. Remove the properties (from ``$sessionDriver`` to ``$sessionDBGroup``) in
+   **app/Config/App.php**.
+
 Breaking Enhancements
 *********************