Fixing wrong parameter name in redirecting in config

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.2+
| Fixed tickets | None

I am also willing to submit an additionnal section on how to redirect to route instead of path with the controller `FrameworkBundle:Redirect:redirect`. This one is actually using a parameter named `route`.