[Security] Remove wrong sentence about ACL

Author: Robin Chalas

src/Symfony/Component/Security/README.md

@@ -6,7 +6,7 @@ application. It ships with facilities for authenticating using HTTP basic or
 digest authentication, interactive form login or X.509 certificate login, but
 also allows you to implement your own authentication strategies. Furthermore,
 the component provides ways to authorize authenticated users based on their
-roles, and it contains an advanced ACL system.
+roles.
 
 Resources
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