documentation update + code fixes

docs/enhancing-and-overriding/how-to-enhance-a-user-model.md

@@ -73,3 +73,5 @@ class ProfileController extends Controller
 
 > This is absolutely good way to extend almost any class of the extension. For more information you could
 > check `Da\User\Bootstrap` class file to see what you have in your control.
+
+© [2amigos](http://www.2amigos.us/) 2013-2017

docs/enhancing-and-overriding/overriding-classes.md

@@ -0,0 +1,106 @@
+Overriding Classes
+==================
+
+This module makes extensive use of the Yii2's Dependency Injection Container. The module has a special attribute 
+named `classMap` where it allows you to override specific classes. 
+
+The following are the classes that you can override throughout that attribute: 
+
+- Model Classes (AR)
+    - User 
+    - SocialNetworkAccount
+    - Profile
+    - Token
+    - Assignment
+    - Permission
+    - Role
+- Search Classes 
+    - UserSearch
+    - PermissionSearch
+    - RoleSearch
+- Form Classes
+    - RegistrationForm
+    - ResendForm
+    - LoginForm
+    - SettingsForm
+    - RecoveryForm
+    
+
+How to Override
+---------------
+
+The `classMap` contains an easy to recognize name and their correspondent definition. The default configuration can be 
+seen at the `Bootstrap` class:
+
+```php
+$defaults = [
+    // --- models
+    'User' => 'Da\User\Model\User',
+    'SocialNetworkAccount' => 'Da\User\Model\SocialNetworkAccount',
+    'Profile' => 'Da\User\Model\Profile',
+    'Token' => 'Da\User\Model\Token',
+    'Assignment' => 'Da\User\Model\Assignment',
+    'Permission' => 'Da\User\Model\Permission',
+    'Role' => 'Da\User\Model\Role',
+    // --- search
+    'UserSearch' => 'Da\User\Search\UserSearch',
+    'PermissionSearch' => 'Da\User\Search\PermissionSearch',
+    'RoleSearch' => 'Da\User\Search\RoleSearch',
+    // --- forms
+    'RegistrationForm' => 'Da\User\Form\RegistrationForm',
+    'ResendForm' => 'Da\User\Form\ResendForm',
+    'LoginForm' => 'Da\User\Form\LoginForm',
+    'SettingsForm' => 'Da\User\Form\SettingsForm',
+    'RecoveryForm' => 'Da\User\Form\RecoveryForm',
+];
+```
+
+As you can see, the only thing we need to do is actually modify its definition. For example, the following configuration 
+will override the `RegistrationForm` class:
+
+```php 
+namespace app\forms;
+
+use Da\User\Form\RegistrationForm as BaseForm;
+
+
+class RegistrationForm extends BaseForm {
+
+    /**
+     * Override from parent
+     */
+    public function rules() {
+        // your logic
+    }
+}
+
+```
+Now, to tell the module to use your class instead, you simply need to update the definition of that class into the 
+the `Module::classMap` attribute.
+
+```php
+\\ ... 
+'modules' => [
+    'user' => [
+        'class' => Da\User\Module::class,
+        'classMap' => [
+            'RegistrationForm' => 'app\forms\RegistrationForm'
+        ]
+    ]
+]
+```
+
+The definition can be any of the following (from Yii2's DI container): 
+
+- a **PHP callable**: The callable will be executed when `Container::get()]]` is invoked. The signature of the callable
+  should be `function ($container, $params, $config)`, where `$params` stands for the list of constructor
+  parameters, `$config` the object configuration, and `$container` the container object. The return value
+  of the callable will be returned by `Container::get()]]` as the object instance requested.
+- a **configuration array**: the array contains name-value pairs that will be used to initialize the property
+  values of the newly created object when `Container::get()]]` is called. The `class` element stands for the
+  the class of the object to be created. If `class` is not specified, `$class` will be used as the class name.
+- a **string**: a class name, an interface name or an alias name.
+
+
+
+> See [how to enhance a User model](how-to-enhance-a-user-model.md) guide to see a practical example.