'authclient' docs adjusted

extensions/authclient/README.md

@@ -32,7 +32,7 @@ It covers OpenID, OAuth1 and OAuth2 protocols.
 
 You need to setup auth client collection application component:
 
-```
+```php
 'components' => [
     'authClientCollection' => [
         'class' => 'yii\authclient\Collection',
@@ -53,7 +53,7 @@ You need to setup auth client collection application component:
 
 Then you need to add [[yii\authclient\AuthAction]] to some of your web controllers:
 
-```
+```php
 class SiteController extends Controller
 {
     public function actions()
@@ -76,7 +76,7 @@ class SiteController extends Controller
 
 You may use [[yii\authclient\widgets\AuthChoice]] to compose auth client selection:
 
-```
+```php
 <?= yii\authclient\widgets\AuthChoice::widget([
      'baseAuthUrl' => ['site/auth']
 ]) ?>
@@ -132,7 +132,8 @@ it may be not enough to access full external API functionality. This method is m
 fetch the external user account data.
 To use API calls, you need to setup [[yii\authclient\BaseOAuth::apiBaseUrl]] according to the
 API specification. Then you can call [[yii\authclient\BaseOAuth::api()]] method:
-```
+
+```php
 use yii\authclient\OAuth2;
 
 $client = new OAuth2;
@@ -164,6 +165,33 @@ Following predefined auth clients are available:
 Please, refer to the particular client class documentation for its actual usage.
 
 
+Customize auth clients
+----------------------
+
+All predefined auth clients have a default configuration like `authUrl`, `apiBaseUrl` and so on.
+However in some cases you may want to change these values in order to achieve some specific results.
+For example: using `yii\authclient\clients\Facebook` you may want the auth window appear in popup display
+mode, which is setup via `authUrl`:
+
+```php
+'components' => [
+    'authClientCollection' => [
+        'class' => 'yii\authclient\Collection',
+        'clients' => [
+            'facebook' => [
+                'class' => 'yii\authclient\clients\Facebook',
+                // Facebook login form will be displayed in 'popup' mode
+                'authUrl' => 'https://www.facebook.com/dialog/oauth?display=popup',
+                'clientId' => 'facebook_client_id',
+                'clientSecret' => 'facebook_client_secret',
+            ],
+        ],
+    ]
+    ...
+]
+```
+
+
 Creating your own auth clients
 ------------------------------
 
@@ -178,7 +206,7 @@ for your extension:
 At this stage you can determine auth client default name, title and view options, declaring
 corresponding methods:
 
-```
+```php
 use yii\authclient\OAuth2;
 
 class MyAuthClient extends OAuth2
@@ -211,7 +239,7 @@ All you need is specify auth URL, by redeclaring "authUrl" field.
 You may also setup default required and/or optional attributes.
 For example:
 
-```
+```php
 use yii\authclient\OpenId;
 
 class MyAuthClient extends OpenId
@@ -239,7 +267,7 @@ You will need to specify:
 
 For example:
 
-```
+```php
 use yii\authclient\OAuth2;
 
 class MyAuthClient extends OAuth2
@@ -273,7 +301,7 @@ You will need to specify:
 
 For example:
 
-```
+```php
 use yii\authclient\OAuth1;
 
 class MyAuthClient extends OAuth1