minor #3472 Fixed versionadded inconsistencies in Symfony 2.5+ (danielcsgomes)

This PR was merged into the master branch.

Discussion
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Fixed `versionadded` inconsistencies in Symfony 2.5+

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.5+
| Fixed tickets | N/A

Same as #3471 - Founded some `versionadded` blocks that does not follow the "standard" of having the ".. was introduced in Symfony 2.x" or similar sentence.

Commits
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8beb570 Fixed `versionadded` inconsistencies

Author: weaverryan

cookbook/security/acl_advanced.rst

@@ -50,7 +50,7 @@ your application. Each role, or user has its own security identity.
     if for any reason, a user's username was to change, you must ensure its
     security identity is updated too. The
     :method:`MutableAclProvider::updateUserSecurityIdentity() <Symfony\\Component\\Security\\Acl\\Dbal\\MutableAclProvider::updateUserSecurityIdentity>`
-    method is there to handle the update.
+    method is there to handle the update, it was introduced in Symfony 2.5.
 
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