docs: add note for DST and Time::difference()

Author: kenjis

user_guide_src/source/libraries/time.rst

@@ -379,6 +379,15 @@ the original time:
 
 .. literalinclude:: time/039.php
 
+.. note:: Prior to v4.4.7, Time always converted the time zones to UTC before
+    comparison. This could lead to unexpected results when containing a day
+    differed from 24 hours due to Daylight Saving Time (DST).
+
+    Starting with v4.4.7, when comparing date/times that are in the same
+    time zone, the comparison is performed as is, without conversion to UTC.
+
+        .. literalinclude:: time/042.php
+
 You can use either ``getX()`` methods, or access the calculate values as if they were properties:
 
 .. literalinclude:: time/040.php

user_guide_src/source/libraries/time/042.php

@@ -0,0 +1,12 @@
+<?php
+
+use CodeIgniter\I18n\Time;
+
+// 31 Mar 2024 - Daylight Saving Time Starts
+$current = Time::parse('2024-03-31', 'Europe/Madrid');
+$test    = Time::parse('2024-04-01', 'Europe/Madrid');
+
+$diff = $current->difference($test);
+
+echo $diff->getDays(); // 0 in v4.4.6 or before
+                       // 1 in v4.4.7 or later