improve README example

README.md

@@ -7,28 +7,39 @@ cycle-scheduler is a simple scheduler lib, handling tasks and executes them at r
 ## Examples
 * Init a new scheduler with 4 workers
 ```go
+package main
+
 import (
 	"context"
+	"time"
 
 	scheduler "gitea.thegux.fr/rmanach/cycle-scheduler.git"
 )
 
-ctx := context.Background()
+func main() {
+	ctx, fnCancel := context.WithCancel(context.Background())
 	s := scheduler.NewSchedulerCycle(ctx, 4)
 
 	// add a task with an execution interval of 2 ms (executed every 2 ms)
 	// and a maximum duration of 30 second.
-taskID := s.Delay(
+	s.Delay(
 		func(ctx context.Context) (any, error) {
 			// ...
-		return any, nil
+			return nil, nil
 		},
 		scheduler.WithExecInterval(2*time.Millisecond),
-	scheduler.WithMaxDuration(30*time.Second)
+		scheduler.WithMaxDuration(30*time.Second),
 	)
 
+	// stop the program after 5 seconds
+	go func() {
+		time.Sleep(5 * time.Second)
+		fnCancel()
+	}()
+
 	<-ctx.Done()
 	<-s.Done()
+}
 ```
 
 **NOTE**: for `Delay` optionals arguments, check the `NewTask` method documentation for more details.