[Notifier] Remove version added by mistake

Author: maxim-dovydenok-busuu

notifier/chatters.rst

@@ -223,10 +223,6 @@ The result will be something like:
 .. image:: /_images/notifier/slack/message-reply.png
    :align: center
 
-.. versionadded:: 5.3
-
-    The ``threadTs()`` method was introduced in Symfony 5.3.
-
 Updating a Slack Message
 ----------------------------------
 
@@ -251,10 +247,6 @@ Use full message id to create
     $options = new UpdateMessageSlackOptions($fullMessageId);
     $chatter->send(new ChatMessage('Updated message', $options));
 
-.. versionadded:: 6.2
-
-    The ``UpdateMessageSlackOptions`` class was introduced in Symfony 6.2.
-
 Adding Interactions to a Discord Message
 ----------------------------------------