Merge branch '4.4' into 5.3

* 4.4:
  Update framework.rst

Author: javiereguiluz

reference/configuration/framework.rst

@@ -40,6 +40,8 @@ recommended length is around 32 characters.
 In practice, Symfony uses this value for encrypting the cookies used
 in the :doc:`remember me functionality </security/remember_me>` and for
 creating signed URIs when using :ref:`ESI (Edge Side Includes) <edge-side-includes>`.
+That's why you should treat this value as if it were a sensitive credential and
+**never make it public**.
 
 This option becomes the service container parameter named ``kernel.secret``,
 which you can use whenever the application needs an immutable random string