[ci skip] Add a changelog entry for class file naming rule change
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index efbe860..2bd34c3 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -19,6 +19,7 @@
 -  General Changes
 
    -  PHP 5.1.6 is no longer supported. CodeIgniter now requires PHP 5.2.4.
+   -  Changed filenaming convention (class file names now must be Ucfirst and everything else in lowercase).
    -  ``$_SERVER['CI_ENV']`` can now be set to control the ``ENVIRONMENT`` constant.
    -  Added an optional backtrace to php-error template.
    -  Added Android to the list of user agents.