doc update [skip ci]

framework/behaviors/SluggableBehavior.php

@@ -12,7 +12,7 @@ use yii\db\BaseActiveRecord;
 use yii\helpers\Inflector;
 
 /**
- * SluggableBehavior automatically fills the specified attribute with the transliterated and adjusted version to use in URLs.
+ * SluggableBehavior automatically fills the specified attribute with a value that can be used a slug in a URL.
  *
  * To use SluggableBehavior, insert the following code to your ActiveRecord class:
  *
@@ -25,6 +25,7 @@ use yii\helpers\Inflector;
  *         [
  *             'class' => SluggableBehavior::className(),
  *             'attribute' => 'title',
+ *             // 'slugAttribute' => 'slug',
  *         ],
  *     ];
  * }
@@ -36,13 +37,26 @@ use yii\helpers\Inflector;
 class SluggableBehavior extends AttributeBehavior
 {
     /**
-     * @var string
+     * @var string the attribute that will receive the slug value
      */
     public $slugAttribute = 'slug';
     /**
-     * @var string
+     * @var string the attribute whose value will be converted into a slug
      */
     public $attribute;
+    /**
+     * @var string|callable the value that will be used as a slug. This can be an anonymous function
+     * or an arbitrary value. If the former, the return value of the function will be used as a slug.
+     * The signature of the function should be as follows,
+     *
+     * ```php
+     * function ($event)
+     * {
+     *     // return slug
+     * }
+     * ```
+     */
+    public $value;
 
     /**
      * @inheritdoc
@@ -56,7 +70,7 @@ class SluggableBehavior extends AttributeBehavior
         }
 
         if ($this->attribute === null && $this->value === null) {
-            throw new InvalidConfigException('Either "attribute" or "value" properties must be specified.');
+            throw new InvalidConfigException('Either "attribute" or "value" property must be specified.');
         }
     }