minor #18195 Set request stateless only if the attribute is not defined (alamirault)

This PR was squashed before being merged into the 6.3 branch.

Discussion
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Set request stateless only if the attribute is not defined

symfony/symfony#48044 added in 6.3 was updated in symfony/symfony#49997.

This PR ajust behavior documentation

Commits
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20ee4d7 Set request stateless only if the attribute is not defined

Author: OskarStark

reference/configuration/security.rst

@@ -1006,7 +1006,8 @@ the session must not be used when authenticating users:
             // ...
         };
 
-Routes under this firewall will be :ref:`configured stateless <stateless-routing>`.
+Routes under this firewall will be :ref:`configured stateless <stateless-routing>`
+when they are not explicitly configured stateless or not.
 
 .. versionadded:: 6.3