guide WIP [skip ci]

docs/guide/start-gii.md

 Generating Code with Gii
 ========================
 
-> Note: This section is under development.
+In this section, we will describe how to use [Gii](tool-gii.md) to automatically generate the code
+that implements some common features. To achieve this goal, all you need is just to enter the needed
+information according to the instructions showing on the Gii Web pages.
+
+Through this tutorial, you will learn
+
+* How to enable Gii in your application;
+* How to use Gii to generate an Active Record class;
+* How to use Gii to generate the code implementing the CRUD operations for a DB table.
+* How to customize the code generated by Gii.
+
+
+Starting Gii
+------------
+
+[Gii](tool-gii.md) is provided by Yii in terms of a [module](structure-modules.md). You can enable Gii
+by configuring it in the [[yii\base\Application::modules|modules]] property of the application. In particular,
+you may find the following code is already given in the `config/web.php` file - the application configuration,
+
+```php
+$config = [ ... ];
+
+if (YII_ENV_DEV) {
+    $config['bootstrap'][] = 'gii';
+    $config['modules']['gii'] = 'yii\gii\Module';
+}
+```
+
+The above configuration states that when in [development environment](concept-configurations.md#environment-constants),
+the application should include a module named `gii` which is of class [[yii\gii\Module]].
+
+If you check the [entry script](structure-entry-scripts.md) `web/index.php` of your application, you will
+find the following line which essentially makes `YII_ENV_DEV` to be true.
+
+```php
+defined('YII_ENV') or define('YII_ENV', 'dev');
+```
+
+Therefore, your application has already enabled Gii, and you can access it via the following URL:
+
+```
+http://hostname/index.php?r=gii
+```
+
+
+Generating an Active Record Class
+---------------------------------
+
+To use Gii to generate an Active Record class, select the "Model Generator". You will see the following page:
+
+
+Fill out the form as follows:
+
+* Table Name: `country`
+* Model Class: `Country`
+
+Click on the "Preview" button. You will see `models/Country.php` is listed in the result.
+You may click on it to preview its content.
+
+
+Because in the last section, you have already created the same file `models/Country.php`, if you click
+the `diff` button next to the file name, you will see the difference between the code to be generated
+and the code that you have already written.
+
+Check the checkbox next to "overwrite" and then click on the "Generate" button. You will see
+a confirmation page indicating the code has been successfully generated and your existing `models/Country.php`
+is overwritten with the newly generated code.
+
+
+Generating CRUD Code
+--------------------
+
+To create CRUD code, select the "CRUD Generator". Fill out the form as follows:
+
+* Model Class: `app\models\Country`
+* Search Model Class: `app\models\CountrySearch`
+* Controller Class: `app\controllers\CountryController`
+
+Click on the "Preview" button. You will see a list of files to be generated, as shown below.
+
+
+Make sure you have checked the checkbox for the `controllers/CityController.php` line. This is needed
+because you have already created this file in the previous section and the file needs to be overwritten
+to have full CRUD support.
+
+
+How It Works
+------------
+
+To see how it works, use your browser to access the following URL:
+
+```
+http://hostname/index.php?r=country/index
+```
+
+You will see a data grid showing the countries in the database table. You may sort the grid
+or filter it by entering filter conditions in the column headers.
+
+For each country displayed in the grid, you may choose to view its detail, update it or delete it.
+You may also click on the "Create Country" button on top of the grid to create a new country.
+
+The following is the list of the generated files in case you want to dig out how these features are implemented,
+or if you want to customize them.
+
+* Controller: `controllers/CountryController.php`
+* Models: `models/Country.php` and `models/CountrySearch.php`
+* Views: `views/country/*.php`
+
+> Info: Gii is designed to be a highly customizable and extensible code generation tool. Using it wisely
+  can greatly accelerate your application development speed. For more details, please refer to
+  the [Gii](tool-gii.md) section.
+
+
+Summary
+-------
+
+In this section, you have learned how to use Gii to generate the code that implements a complete
+set of CRUD features regarding a database table.

extensions/gii/generators/crud/Generator.php

@@ -110,7 +110,7 @@ class Generator extends \yii\gii\Generator
             'indexWidgetType' => 'This is the widget type to be used in the index page to display list of the models.
                 You may choose either <code>GridView</code> or <code>ListView</code>',
             'searchModelClass' => 'This is the name of the search model class to be generated. You should provide a fully
-                qualified namespaced class name, e.g., <code>app\models\search\PostSearch</code>.',
+                qualified namespaced class name, e.g., <code>app\models\PostSearch</code>.',
         ]);
     }