Add mkdocs and change menu names to avoid margin collisions (#468)

docs/guides/how-to-switch-identities.md

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+How to Switch Identities with a user
+====================================
+
+If you are admin, you can impersonate (switch identities with another user). This action is taken when you, as an admin, 
+needs to check the panel of a user. Whether for support or simply checking whether is using correctly your system 
+according to your terms and conditions. 
+
+The default view of this module provides the mechanism on the grid that displays the users by placing a user icon on 
+its actions column. Once, clicked, it will call the **/user/admin/switch-identity** and make the transition. Then will 
+redirect you to the index page (`goHome()`) and is there where you will have to take the correspondent actions to 
+display the views appropriated for that user. 
+ 
+How to rollback to admin user
+-----------------------------
+The way to do it is by calling that action again. The link to do that could be written like this: 
+
+```php
+$module = Yii::$app->getModule('user');
+
+if(Yii::$app->session->has($module->switchIdentitySessionKey)) {
+   echo Html::a('Switch to Admin', ['/user/admin/switch-identity'], ['data-method' => 'post']);
+}
+```
+> Note: If you use RBAC we can add access for all user to to this action for back to original user available.
+```php
+...
+    'modules' => [
+        'user' => [
+            'controllerMap' => [
+                'admin' => [
+                    'class' => Da\User\Controller\AdminController::class,
+                    'as access' => [
+                        'class' => yii\filters\AccessControl::class,
+                        'rules' => [
+                            ['allow' => true, 'actions' => ['switch-identity']],
+                            ['allow' => true, 'permissions' => ['administrateUser']],
+                        ],
+                    ],
+                ],
+            ],
+        ],
+    ],
+...
+``` 
+> Also you can define access role `'administratorPermissionName' => 'admin',` where `admin` is have `administrateUser` permission
+```php
+...
+    'modules' => [
+        'user' => [
+            'class' => Da\User\Module::class,
+            'administratorPermissionName' => 'admin',
+        ],
+    ],
+...
+``` 
+
+
+Check the [switchIdentitySessionKey](../install/configuration-options.md#switchidentitysessionkey) documentation  
+for further information regarding this configuration option. 
+
+© [2amigos](http://www.2amigos.us/) 2013-2019