Add a version added block

Author: natewiebe13

translation.rst

@@ -295,6 +295,10 @@ using PHP's :phpclass:`MessageFormatter` class. Read more about this in
 Translatable Objects
 --------------------
 
+.. versionadded:: 5.2
+
+    Translatable objects were introduced in Symfony 5.2.
+
 Sometimes you may want to create a message, but at the time of creation aren't
 sure how it would be translated. For example, it could be translated multiple
 times if intended to be displayed to multiple users.