Routing: add "versionadded" for the "_fragment" parameter

Author: alexislefebvre

routing.rst

@@ -476,6 +476,10 @@ that are special: each adds a unique piece of functionality inside your applicat
     Used to set the request format (:ref:`read more <routing-format-param>`).
 
 ``_fragment``
+
+ .. versionadded:: 3.2
+    The ``_fragment`` parameter was introduced in Symfony 3.2.
+
     Used to set the fragment identifier, the optional last part of a URL that
     starts with a ``#`` character and is used to identify a portion of a document.