[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 | 
Ah, I just had a chance to try this again. It's `0.0.0.0` that works. If you start that up inside the VM, you'll be able to access the site from outside the vm (e.g. via 192.168.56.150, if that's the address to your VM).