Fix docs for ViewStore.binding overload. (#321)

* Fix docs for ViewStore.binding overload.

* wip

* Update Sources/ComposableArchitecture/ViewStore.swift

Co-authored-by: Stephen Celis <[email protected]>

Author: mbrandonw

Sources/ComposableArchitecture/ViewStore.swift

@@ -170,7 +170,7 @@ public final class ViewStore<State, Action>: ObservableObject {
   ///
   /// For example, a text field binding can be created like this:
   ///
-  ///     struct State { var name = "" }
+  ///     typealias State = String
   ///     enum Action { case nameChanged(String) }
   ///
   ///     TextField(
@@ -199,14 +199,14 @@ public final class ViewStore<State, Action>: ObservableObject {
   ///
   /// For example, an alert binding can be dealt with like this:
   ///
-  ///     struct State { var alert: String? }
+  ///     typealias State = String
   ///     enum Action { case alertDismissed }
   ///
   ///     .alert(
-  ///       item: self.store.binding(
+  ///       item: viewStore.binding(
   ///         send: .alertDismissed
   ///       )
-  ///     ) { alert in Alert(title: Text(alert.message)) }
+  ///     ) { title in Alert(title: Text(title)) }
   ///
   /// - Parameters:
   ///   - action: The action to send when the binding is written to.