minor #13366 [Routing] added missing "version-added" for i18n routes (HeahDude)

This PR was merged into the 4.4 branch.

Discussion
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[Routing] added missing "version-added" for i18n routes

To revert in 5.0.

Commits
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c651749 [Routing] added missing "version-added" for i18n routes

Author: javiereguiluz

routing.rst

@@ -38,7 +38,7 @@ following configuration file:
     controllers:
         resource: '../../src/Controller/'
         type: annotation
-        
+
     kernel:
         resource: ../../src/Kernel.php
         type: annotation
@@ -1655,6 +1655,10 @@ these routes.
 Localized Routes (i18n)
 -----------------------
 
+..version-added:: 4.1
+
+    The i18n routing has been introduced in Symfony 4.1.
+
 If your application is translated into multiple languages, each route can define
 a different URL per each :doc:`translation locale </translation/locale>`. This
 avoids the need for duplicating routes, which also reduces the potential bugs: