docs: add changelog

Author: kenjis

user_guide_src/source/changelogs/v4.5.5.rst

@@ -30,6 +30,10 @@ Deprecations
 Bugs Fixed
 **********
 
+- **URL Helper:** The bug where the regular expression of :php:func:`auto_link()`
+  was old has been fixed. As a result of this fix, the same regular expression as
+  CodeIgniter 3 is now used.
+
 See the repo's
 `CHANGELOG.md <https://github.com/codeigniter4/CodeIgniter4/blob/develop/CHANGELOG.md>`_
 for a complete list of bugs fixed.