Change documented options to the easiest one

src/freedombone

@@ -353,7 +353,7 @@ CJDNS_PORT=
 
 function show_help {
   echo ''
-  echo 'freedombone -d [domain] -u [username] -s [system type]'
+  echo 'freedombone -c [configuration file]'
   echo ''
   echo '  -h --help             Show help'
   echo '     menuconfig         Easy interactive installation'