Update service_container/tags.rst

Co-Authored-By: XuruDragon <xurudragon@gmail.com>

Author: deguif

service_container/tags.rst

@@ -700,7 +700,7 @@ to get an array and then retrieve the ``handler_two`` handler :
 
                     <service id="App\HandlerCollection">
                         <!-- inject all services tagged with app.handler as first argument -->
-                        <argument type="tagged" tag="app.handler" index-by="index"/>
+                        <argument type="tagged" tag="app.handler" index-by="index" />
                     </service>
                 </services>
             </container>