A bit more docs on console applications

docs/guide/console.md

@@ -7,7 +7,7 @@ consists of one or more [[\yii\console\Controller]] (often referred to as comman
 Usage
 -----
 
-User executes controller action using the following syntax:
+You can execute controller action using the following syntax:
 
 ```
 yii <route> [--param1=value1 --param2 ...]
@@ -20,13 +20,54 @@ line like the following:
 yii migreate/create --migrationTable=my_migration
 ```
 
+In the above `yii` is console application entry script described below.
+
 Entry script
 ------------
 
+Console application entry script is typically called `yii`, located in your application root directory and contains
+code like the following:
+
+```php
+#!/usr/bin/env php
+<?php
+/**
+ * Yii console bootstrap file.
+ *
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+defined('YII_DEBUG') or define('YII_DEBUG', true);
+
+// fcgi doesn't have STDIN defined by default
+defined('STDIN') or define('STDIN', fopen('php://stdin', 'r'));
+
+require(__DIR__ . '/vendor/autoload.php');
+require(__DIR__ . '/vendor/yiisoft/yii2/yii/Yii.php');
+
+$config = require(__DIR__ . '/config/console.php');
+
+$application = new yii\console\Application($config);
+$exitCode = $application->run();
+exit($exitCode);
+
+```
+
+This script is a part of your application so you're free to adjust it. There `YII_DEBUG` can be turned off if you do
+not want to see stacktrace on error and want to improve overall performance. In both basic and advanced application
+templates it is enabled to provide more developer-friendly environment.
 
 Configuration
 -------------
 
+As can be seen in the code above, console application uses its own config files named `console.php` so you need to
+configure database connection and the rest of the components you're going to use there in that file. If web and console
+application configs have a lot in common it's a good idea to move matching parts into their own config files as it was
+done in advanced application template.
+
+
 Creating your own console commands
 ----------------------------------
 
@@ -37,3 +78,6 @@ Creating your own console commands
 ### Parameters
 
 ### Return codes
+
+Using return codes is the best practice of console application development. If command returns `0` it means everything
+is OK. If it is a number more than zero, we have an error and integer returned is the error code.
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