Prevent non-existent help handbook from populating the main handbook table of contents.

systemsettings/systemsettings.desktop

@@ -3,7 +3,13 @@ Encoding=UTF-8
 Exec=systemsettings -caption "%c" %i %m
 Icon=systemsettings
 Type=Application
-DocPath=systemsettings/index.html
+# Restore the following key and remove this comment when a help handbook
+# is written. Disabling this key prevents populating the main handbook
+# table of contents with a non-existent document, which results in a
+# main handbook error message of
+# 'There is no documentation available for /xyz/index.html.'
+# Also disable this key when there exists only a useless template handbook.
+# DocPath=systemsettings/index.html
 X-TDE-StartupNotify=true
 
 Name=System Settings