[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.
A question for native English speakers: I think that the `translate` word is too related to translating  (human) languages. Could it be better to use `switch`, `transform`, etc. or is it OK to keep using `translate`?