Improve producer-consumer examples

* Use setImmediate instead of while(true)
* Add another parallel task

Author: aqrln

producer-consumer-send.js

@@ -31,6 +31,10 @@ function* consume() {
 let consumer = consume();
 let producer = produce(consumer);
 consumer.next();
-while (true) {
+
+function step() {
   producer.next();
+  setImmediate(step);
 }
+
+step();

producer-consumer.js

@@ -26,7 +26,21 @@ function* consume() {
   }
 }
 
+function* anotherTask() {
+  while (true) {
+    yield* sleep(1000);
+    console.log('Hello!\n');
+  }
+}
+
 let consumer = consume();
-while (true) {
+let task = anotherTask();
+
+function step() {
   consumer.next();
+  task.next();
+
+  setImmediate(step);
 }
+
+step();