Updated talk on the history of Shortcuts, my co-worker named Siri, and the new iOS 12 APIs you can use to start creating your own (semi-limited) shortcuts.
Now with way more info about configuring responses, setting up an intents UI extension, and some crazy things one developer has done to try to bend Intent-powered shortcuts to his will.
Sample code available at https://github.com/designatednerd/TravelPlanner