docs: typo (fluttercommunity#508)

README.md

@@ -28,7 +28,7 @@ Before registering any task, the WorkManager plugin must be initialized.
 @pragma('vm:entry-point') // Mandatory if the App is obfuscated or using Flutter 3.1+
 void callbackDispatcher() {
   Workmanager().executeTask((task, inputData) {
-    print("Native called background task: $backgroundTask"); //simpleTask will be emitted here.
+    print("Native called background task: $task"); //simpleTask will be emitted here.
     return Future.value(true);
   });
 }