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

knetwalk/src/knetwalk.desktop

@@ -1,7 +1,13 @@
 [Desktop Entry]
 Type=Application
 Exec=knetwalk -caption "%c" %i %m
-DocPath=knetwalk/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=knetwalk/index.html
 Name=KNetwalk
 Name[bn]=কে-নেটওয়াক
 Name[fi]=KNetwalk