Add missing SuluMedia Bundle Configurations

[alexander-schranz]

In #623 we added some configuration to the doc. We should also add the other available options to the configuration docs.

[TheCadien]

A little bit offtopic.
@alexander-schranz , what do you think about an example for Extending Entities with the MediaBundle. (SuluMedia Attribute). And a Example for view Images in a ListView. Is the SuluMedia Bundle the right place ?
Im interested in do that

[niklasnatter]

We dont have a lot of documentation about custom entities at the moment, so not sure what would be the best place for this. Would be okay for me to add a Use media in custom entity section - i think its better than having no documentation at all 🙂

[alexander-schranz]

We had something similar one a project documentation there was a section Override Entities and then for every entity was a new sub section e.g.: Override Media Entity.

[alexander-schranz]

Docs did there look like this:

## Override Entities

### Override Media Entity

Create your new product entity class:

```php
<?php
// src/Entity/Product.php

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;
use .......\Media as SuluMedia;

/**
 * @ORM\Table(name="me_media")
 * @ORM\Entity
 */
class Media extends SuluMedia
{
}
```

Configure your new model class:

```yaml
# config/packages/sulu_product.yaml

sulu_media:
     objects:
         media:
             model: 'App\Entity\Media'
```

To add new fields to your entity have a look at the [Doctrine Mapping Documentation](https://www.doctrine-project.org/projects/doctrine-orm/en/2.7/reference/basic-mapping.html);

[TheCadien]

@alexander-schranz I meant more the direction of bring the Media Bundle into your own Entity.
As an example "event" has a property "image" which has a doctrine relationship to "media".

And the doc should contain how about doctrine config (yml or xml) establishes this relationship.
Like here in Contact.
https://github.com/sulu/sulu/blob/2.x/src/Sulu/Bundle/ContactBundle/Resources/config/doctrine/Contact.orm.xml#L44

Another part should be how you can show the media in your ListView.
Like here:
https://github.com/sulu/sulu/blob/2.x/src/Sulu/Bundle/ContactBundle/Resources/config/lists/contacts.xml#L45

[alexander-schranz]

Oh yeah then Usage media with custom entity or something similar would make sense.