Merge branch '5.4' into 6.0

* 5.4:
  Add redirections for deleted pages
  Merge standalone Security component docs with Security guide

Author: javiereguiluz

_build/redirection_map

@@ -533,6 +533,11 @@
 /security/authenticator_manager /security
 /security/multiple_guard_authenticators /security/entry_point
 /security/guard_authentication /security/custom_authenticator
+/components/security/authentication /security#authenticating-users
+/components/security/authorization /security#access-control-authorization
+/components/security/firewall /security#the-firewall
+/components/security/secure_tools /security/passwords
+/components/security /security
 /email /mailer
 /frontend/assetic /frontend
 /frontend/assetic/index /frontend