Set debounce duration to 300ms (#2525)

The docs and code comments suggest that the debounce is 300ms, not 3 seconds. This ensures the example works as described.

Examples/Search/Search/SearchView.swift

@@ -165,7 +165,7 @@ struct SearchView: View {
       }
       .task(id: viewStore.searchQuery) {
         do {
-          try await Task.sleep(for: .seconds(3))
+          try await Task.sleep(for: .milliseconds(300))
           await viewStore.send(.searchQueryChangeDebounced).finish()
         } catch {}
       }