Update routing.rst

Co-authored-by: Oskar Stark <oskarstark@googlemail.com>

Author: ThomasLandauer

routing.rst

@@ -379,7 +379,7 @@ You can also use these functions:
 ``service(string $alias)``
     Returns a routing condition service.
     You'll have to add the ``#[AsRoutingConditionService]`` attribute or ``routing.condition_service``
-    tag to your service if you want to use it in the condition. Example:
+    tag to your service if you want to use it in the condition::
     
     .. code-block:: php