docs: add changelog and upgrade

Author: kenjis

user_guide_src/source/changelogs/v4.4.7.rst

@@ -14,6 +14,11 @@ Release Date: Unreleased
 BREAKING
 ********
 
+- In previous versions, when comparing dates with ``Time::difference()``,
+  unexpected results were returned if the date included a day different from 24
+  hours due to Daylight Saving Time (DST). This bug has been fixed. See
+  :ref:`Note in Times and Dates <time-viewing-differences>` for details.
+
 ***************
 Message Changes
 ***************

user_guide_src/source/installation/upgrade_447.rst

@@ -28,6 +28,21 @@ The error page has been updated. Please update the following files:
 Breaking Changes
 ****************
 
+Time::difference() and DST
+==========================
+
+In previous versions, when comparing dates with ``Time::difference()``, unexpected
+results were returned if the date included a day different from 24 hours due to
+Daylight Saving Time (DST). See :ref:`Note in Times and Dates <time-viewing-differences>`
+for details.
+
+This bug has been fixed, so date comparisons will now be shifted by one day in
+such cases.
+
+In the unlikely event that you wish to maintain the behavior of the previous
+versions, change the time zone of both dates being compared to UTC before passing
+them to ``Time::difference()``.
+
 *********************
 Breaking Enhancements
 *********************

user_guide_src/source/libraries/time.rst

@@ -362,6 +362,8 @@ Works exactly the same as ``isBefore()`` except checks if the time is after the
 
 .. literalinclude:: time/037.php
 
+.. _time-viewing-differences:
+
 Viewing Differences
 ===================