docs: message changes in changelog 4.2.7

Co-authored-by: Pooya Parsa Dadashi <pooya_parsa_dadashi@yahoo.com>

Author: ddevsr

user_guide_src/source/changelogs/v4.2.7.rst

@@ -24,7 +24,7 @@ none.
 Message Changes
 ***************
 
-- Added missing item `valid_json` in `Language/en/Validation.php`
+- Added missing item ``valid_json`` in ``Language/en/Validation.php``
 
 Changes
 *******