Simplify basic usage of schema_to_mapping ?

I'm only starting with converting jsonschema to elasticsearch mappings. Based on the amount of work you provided in this library, I have to admit this is not an easy task.
But still, I have the feeling that it could have some default values to make first steps easier.

For example:

```py
from domapping import schema_to_mapping

mapping = schema_to_mapping(json_schema)
```

Instead of:
```py
from domapping.mapping import ElasticMappingGeneratorConfig, schema_to_mapping
root_url = json_schema.get("id", "")
mapping = schema_to_mapping(json_schema, root_url, {}, ElasticMappingGeneratorConfig())
```

Thanks!

(Just a suggestion, feel free to close this issue)