Minor change: add comment

main.cpp

@@ -98,6 +98,7 @@ int main(int argc, char *argv[]) {
     // -d: only update device-controller firmware
     // -j: only update json-files
     // -o: only execute opkg-commnds
+    // -f: force. update_psa shall always perform a 'git pull'
 
     // Process the actual command line arguments given by the user
     parser.process(a);