Merge branch '3.4' into 4.4

* 3.4:
  Remove file (added by accident)
  add note to use the constraint UserPassword

Author: OskarStark

reference/constraints/UserPassword.rst

@@ -10,6 +10,11 @@ password, but needs to enter their old password for security.
     This should **not** be used to validate a login form, since this is
     done automatically by the security system.
 
+.. note::
+
+    In order to use this constraints, you should have installed the
+    symfony/security-core component with Composer.
+
 ==========  ===================================================================
 Applies to  :ref:`property or method <validation-property-target>`
 Options     - `groups`_