Add important note about delegate actions. (#3135)

Sources/ComposableArchitecture/Documentation.docc/Tutorials/MeetTheComposableArchitecture/02-Navigation/01-YourFirstPresentation/02-01-YourFirstPresentation.tutorial

@@ -256,6 +256,15 @@
  @Code(name: "AddContactFeature.swift", file: 02-01-04-code-0000.swift, previousFile: 02-01-04-code-0000-previous.swift)
  }
 
+ > Important: Delegate actions are the most general way of communicating from the child domain
+ back to the parent, but there are other techniques. We could have also utilized the 
+ [`@Shared`](<doc:Shared>) property wrapper for the collection of sync ups, which would allow
+ the `AddContactFeature` to insert a new contact directly into the parent collection without
+ any further steps. This can be powerful, but we will use delegate actions for this tutorial.
+ To read more about `@Shared` see the <doc:SharingState> article, and see the
+ <doc:BuildingSyncUps> tutorial where we see this technique, in particular in
+ <doc:EditingAndDeletingSyncUp#Deleting-the-sync-up> section.
+
  @Step {
  Handle the new case in the reducer, but we should never actually perform any logic in this
  case. Only the parent should listen for `delegate` actions and respond accordingly.