[Cookbook] add cookbook article for the server:run command

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes (symfony/symfony#3465)
| Applies to    | all
| Fixed tickets | 
How about this (for the same reason as above):

```sphinx
If you want the web server to bind to a different IP address or listen to a different port
just pass these as an argument to the command:
```