[job-queue] Update doc.

Author: makasim

docs/bundle/job_queue.md

@@ -1,32 +1,105 @@
 # Jobs
 
+Use jobs when your message flow has several steps(tasks) which run one after another.
+Also jobs guaranty that job is unique i.e. you cant start new job with same name
+until previous job has finished.
+
+* [Installation](#installation)
 * [Unique job](#unique-job)
 * [Sub jobs](#sub-jobs)
+* [Dependent Job](#dependent-job)
 
+## Installation
 
-Use jobs when your message flow has several steps(tasks) which run one after another.
-Also jobs guaranty that job is unique i.e. you cant start new job with same name
-until previous job has finished.
+The easiest way to install Enqueue's job queues is to by requiring a `enqueue/job-queue-pack` pack. 
+It installs installs everything you need. It also configures everything for you If you are on Symfony Flex.
+  
+```bash
+$ composer require enqueue/job-queue-pack=^0.8
+```
+
+_**Note:** As long as you are on Symfony Flex you are done. If not, keep reading the installation chapter._
+
+* Register installed bundles
+
+```php
+<?php
+// app/AppKernel.php
+
+use Symfony\Component\HttpKernel\Kernel;
+
+class AppKernel extends Kernel
+{
+    public function registerBundles()
+    {
+        $bundles = [
+            new Doctrine\Bundle\DoctrineBundle\DoctrineBundle(),
+            new Enqueue\Bundle\EnqueueBundle(),
+        ];
+        
+        return $bundles;
+    }
+}
+````
+
+* Configure installed bundles:
+
+```yaml
+# app/config/config.yml
+
+enqueue:
+    # plus basic bundle configuration
+    
+    job: true
+
+doctrine:
+    # plus basic bundle configuration
+
+    orm:
+        mappings:
+            EnqueueJobQueue:
+                is_bundle: false
+                type: xml
+                dir: '%kernel.project_dir%/vendor/enqueue/job-queue/Doctrine/mapping'
+                prefix: 'Enqueue\JobQueue\Doctrine\Entity'
+
+```
+
+* Run doctrine schema update command
+
+```bash
+$ bin/console doctrine:schema:update
+```
 
 ## Unique job
 
-Guaranty that there is only single job running with such name. 
+Guarantee that there is only one job with such name running at a time.
+For example you have a task that builds a search index. 
+It takes quite a lot of time and you dont want another instance of same task working at the same time.
+Here's how to do it: 
+
+* Write a job processor class:
 
 ```php
 <?php 
+namespace App\Queue;
+
 use Interop\Queue\PsrMessage;
 use Interop\Queue\PsrProcessor;
 use Interop\Queue\PsrContext;
 use Enqueue\Util\JSON;
 use Enqueue\JobQueue\JobRunner;
 use Enqueue\JobQueue\Job;
+use Enqueue\Client\CommandSubscriberInterface;
 
-class ReindexProcessor implements PsrProcessor
+class SearchReindexProcessor implements PsrProcessor, CommandSubscriberInterface
 {
-    /**
-     * @var JobRunner
-     */
     private $jobRunner;
+    
+    public function __construct(JobRunner $jobRunner) 
+    {
+        $this->jobRunner = $jobRunner;
+    }
 
     public function process(PsrMessage $message, PsrContext $context)
     {
@@ -44,12 +117,42 @@ class ReindexProcessor implements PsrProcessor
 
         return $result ? self::ACK : self::REJECT;
     }
+    
+    public static function getSubscribedCommand() 
+    {
+        return 'search_reindex';
+    }
 }
 ```
 
+* Register it
+
+```yaml
+services:
+  app_queue_search_reindex_processor:
+    class: 'App\Queue\SearchReindexProcessor'
+    arguments: ['@Enqueue\JobQueue\JobRunner']
+    tags:
+        - { name: 'enqueue.client.processor' }
+```
+
+* Schedule command
+
+```php
+<?php
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Enqueue\Client\ProducerInterface;
+
+/** @var ContainerInterface $container  */
+
+$producer = $container->get(ProducerInterface::class);
+
+$producer->sendCommand('search_reindex');
+```
+
 ## Sub jobs
 
-Run several sub jobs in parallel. 
+Run several sub jobs in parallel. The steps are the same as we described above.
 
 ```php
 <?php
@@ -133,6 +236,7 @@ class Step2Processor implements PsrProcessor
 
 Use dependent job when your job flow has several steps but you want to send new message
 just after all steps are finished.
+The steps are the same as we described above.
 
 ```php
 <?php