Update README.md, consistent use of spaces instead of tabs, better examples

bin/single_worker_with_job_class.php

@@ -0,0 +1,21 @@
+<?php
+
+use Toalett\Multiprocessing\Concurrency;
+use Toalett\Multiprocessing\ContextBuilder;
+use Toalett\Multiprocessing\Task\Interval;
+
+require_once __DIR__ . '/../vendor/autoload.php';
+require_once __DIR__ . '/classes/Job.php';
+
+$context = ContextBuilder::create()
+    ->withConcurrency(Concurrency::singleWorker())
+    ->withCleanupInterval(Interval::seconds(0.2))
+    ->build();
+
+for ($i = 0; $i < 3; $i++) {
+    $title = md5(mt_rand());
+    $context->submit(new Job($title));
+}
+
+$context->on('no_workers_remaining', [$context, 'stop']);
+$context->run();