docs: remove text decoration

Author: kenjis

user_guide_src/source/helpers/form_helper.rst

@@ -12,7 +12,7 @@ forms.
 Configuration
 =============
 
-Since ``v4.3.0``, void HTML elements (e.g. ``<input>``) in ``form_helper`` functions have been changed to be HTML5-compatible by default and if you need to be compatible with XHTML, you must set the ``$html5`` property in **app/Config/DocTypes.php** to ``false``.
+Since v4.3.0, void HTML elements (e.g. ``<input>``) in ``form_helper`` functions have been changed to be HTML5-compatible by default and if you need to be compatible with XHTML, you must set the ``$html5`` property in **app/Config/DocTypes.php** to ``false``.
 
 Loading this Helper
 ===================