(documentation) Explain and give an example how to configure Prettier

Could you please update the documentation, to give an example on how to configure Prettier?

I'd like to change some rules, for example, by default it takes my code like:
```php
if(true)
    echo "its true";
```

and converts it to:
```php
if(true) {
    echo "its true";
}
```

I'd like to stop these things and I can't find a way to configure Prettier.

Thank you!
