It's not the url that's put in the cron... it's the filepath to the update.php...
I used the following on the Cron Jobs page of the webpanel:-
/usr/local/php54/bin/php /home/username/domain/update.php --feeds --quiet
Ensure username, domain and any other folders in between are filled in.
Other settings: email blank, Use locking checked (not sure if this is required...), Custom time: every 10 minutes, Every hour, every day, every month every day of the week.