Fixes to the graceful shutdown example (#2552)

* Change error comparison to use errors.Is() and add a line of whitespace before the if statement on graceful shutdown

* Change from log.Fatalf to log.Printf to ensure the graceful shutdown actually works

Co-authored-by: J. J. Bigorra <josep@prowarehouse.nl>
Co-authored-by: thinkerou <thinkerou@gmail.com>

README.md

@@ -1793,8 +1793,8 @@ func main() {
 	// Initializing the server in a goroutine so that
 	// it won't block the graceful shutdown handling below
 	go func() {
-		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
-			log.Fatalf("listen: %s\n", err)
+		if err := srv.ListenAndServe(); err != nil && errors.Is(err, http.ErrServerClosed) {
+			log.Printf("listen: %s\n", err)
 		}
 	}()
 
@@ -1812,6 +1812,7 @@ func main() {
 	// the request it is currently handling
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
+	
 	if err := srv.Shutdown(ctx); err != nil {
 		log.Fatal("Server forced to shutdown:", err)
 	}