docs: remove headings with on items

Author: kenjis

user_guide_src/source/installation/upgrade_438.rst

@@ -12,15 +12,6 @@ Please refer to the upgrade instructions corresponding to your installation meth
     :local:
     :depth: 2
 
-Mandatory File Changes
-**********************
-
-Breaking Changes
-****************
-
-Breaking Enhancements
-*********************
-
 Project Files
 *************