Fix outdated comment (#134)

Author: BafS

README.md

@@ -128,8 +128,8 @@ The runtime for [Symfony](https://symfony.com/) is included in the runtime compo
 
 On Symfony < 5.4 session data will not be properly stored when using a "non-traditional"
 webserver like Bref, Google, ReactPHP, RoadRunner or Swoole. This problem (or missing
-feature) has been added in Symfony 5.4 and 6.0. You need to use the unreleased version
-of `symfony/http-kernel` for sessions to work properly.
+feature) has been added in Symfony 5.4 and 6.0. You need to use `symfony/http-kernel >= 5.4` 
+for sessions to work properly.
 
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