Hi,
This article was not removed.
It's still there. It seems you made a wrong copy / paste. Here is the link to it:
www.hikashop.com/support/documentation/1...s-action-plugin.html
It is certainly possible to develop plugins you add your own triggers, filters and actions to the mass action system following this documentation
Actually, all the triggers, filters and actions that you see there are added by the massaction plugins preinstalled with HikaShop.
I would recommend however not modifying directly the plugins already preinstalled as they are updated each time you update HikaShop and thus you'll loose your changes when you update.
Now, if you develop your own action, you could actually do the same without going through the mass action system, just implementing the onAfterOrderUpdate trigger and running your code when the order is being confirmed. It wouldn't be much more complex and you would have full control of the whole process in your plugin.