editorial fix

Author: Eduardo Fullea

index.html

@@ -1774,7 +1774,7 @@ <h2><a>MessagingFilter</a> Dictionary</h2>
     this identifier are to be provided in the results of this filter.</dd>
 
     <dt>boolean read</dt>
-    <dd>optional whether just read or unread messages are to be provided in the
+    <dd>Indicates whether just read or unread messages are to be provided in the
     results of this filter, respectively if it is set to 'true' or 'false'.</dd>
 
   </dl>