[Serializer] Name Converter

| Q                | A
| --------------- | ---
| Doc fix?      | no
| New docs? | yes symfony/symfony#13120
| Applies to   | 2.7

This is the documentation for the Serializer Name Converter feature.
Why do you guys prefer first name instead of given name? Both Wikipedia and Schema.org use "given name" instead of "first name":
* https://en.wikipedia.org/wiki/Given_name
* http://schema.org/givenName