Add Actions to Transitions to Fire Side Effects

Actions are "fire-and-forget" side effects that are triggered by transitions. We set functions on a transition object's actions property to have them called when a transition is taken.

//...
EVENT_NAME: {
  target: 'name-of-state-to-transition-to',
  actions: [(context, event) => { sideEffectToFire(context, event) }]
}
//...