Mention security voters as the recommended alternative to ACL

Author: javiereguiluz

security/acl.rst

@@ -9,4 +9,7 @@ How to Use Access Control Lists (ACLs)
     ACL support was removed in Symfony 4.0. Install the `Symfony ACL bundle`_
     and refer to its documentation if you want to keep using ACL.
 
+    Alternatively, consider using :doc:`security voters </security/voters>`,
+    the alternative to ACLs recommended by Symfony.
+
 .. _`Symfony ACL bundle`: https://github.com/symfony/acl-bundle

security/acl_advanced.rst

@@ -9,4 +9,7 @@ How to Use advanced ACL Concepts
     ACL support was removed in Symfony 4.0. Install the `Symfony ACL bundle`_
     and refer to its documentation if you want to keep using ACL.
 
+    Alternatively, consider using :doc:`security voters </security/voters>`,
+    the alternative to ACLs recommended by Symfony.
+
 .. _`Symfony ACL bundle`: https://github.com/symfony/acl-bundle