Move sleep and workqueue module doc to README

sleep was broken because the workqueue was declared locally inside init,
further evidence that no one has ever run the examples :-(

kernel_module/workqueue_cheat.c

@@ -1,45 +1,38 @@
-/*
-Usage:
-
-    insmod /workqueue_cheat.ko
-    # dmesg => worker
-    rmmod workqueue_cheat
-
-Creates a separate thread. So init_module can return, but some work will still get done.
-
-Can't call this just workqueue.c because there is already a built-in with that name:
-https://unix.stackexchange.com/questions/364956/how-can-insmod-fail-with-kernel-module-is-already-loaded-even-is-lsmod-does-not
-
-Workqueues are a convenience frontend for kthreads.
-
-Bibliography:
-
-- https://www.ibm.com/developerworks/library/l-tasklets/
-*/
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#workqueue */
 
+#include <linux/delay.h> /* usleep_range */
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/types.h> /* atomic_t */
 #include <linux/workqueue.h>
 
 static struct workqueue_struct *queue;
+static atomic_t run = ATOMIC_INIT(1);
 
 static void work_func(struct work_struct *work)
 {
-	pr_info("worker\n");
+	int i = 0;
+	while (atomic_read(&run)) {
+		pr_info("%d\n", i);
+		usleep_range(1000000, 1000001);
+		i++;
+		if (i == 10)
+			i = 0;
+	}
 }
 
 DECLARE_WORK(work, work_func);
 
 static int myinit(void)
 {
-	queue = create_singlethread_workqueue("myworkqueue");
+	queue = create_workqueue("myworkqueue");
 	queue_work(queue, &work);
 	return 0;
 }
 
 static void myexit(void)
 {
-	/* Waits for jobs to finish. */
+	atomic_set(&run, 0);
 	destroy_workqueue(queue);
 }