[symfony#5521] Added versionadded directive

Author: wouterj

cookbook/web_server/built_in.rst

@@ -48,6 +48,9 @@ can change the socket passing an IP address and a port as a command-line argumen
 
         $ php app/console server:start --force
 
+    .. versionadded:: 2.8
+        The ``--force`` option was introduced in Symfony 2.8.
+
 .. note::
 
     You can use the ``server:status`` command to check if a web server is