Update concept-behaviors.md

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docs/guide/concept-behaviors.md

@@ -249,7 +249,7 @@ $component->detachBehaviors();
 Using `TimestampBehavior` <a name="using-timestamp-behavior"></a>
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-To wrap up, let's take a look at [[yii\behaviors\TimestampBehavior]]. This behavior  supports automatically
+To wrap up, let's take a look at [[yii\behaviors\TimestampBehavior]]. This behavior supports automatically
 updating the timestamp attributes of an [[yii\db\ActiveRecord|Active Record]] model anytime the model is saved (e.g., on insert or update).
 
 First, attach this behavior to the [[yii\db\ActiveRecord|Active Record]] class that you plan to use: