Add documentation about ArrayField for Postgres

[rvanlaar]

Django 1.8 supports the Array data type from postgres.

A simple solution is to use a ListField Serializer:

    field_names = serializers.ListField(child=serializers.CharField(max_length=32, allow_blank=True))

as seen in this issue: https://groups.google.com/forum/#!topic/django-rest-framework/Rolw5yEQ8cU

It would help if this was part of the documentation.

[rvanlaar]

Seems this will be supported in DRF 3.1.

#2496
#2107

[jpadilla]

@rvanlaar yes indeed, we still need docs for those new fields though.

[johnthagen]

@encode / @tomchristie Could this be reopened? I don't see any documentation for ArrayField currently.

[xordoquy]

I think we already got everything covered through ListField

[johnthagen]

I guess it's not immediately clear to me how a ModelSerializer with an ArrayField maps in without an example. Maybe at least mentioning the connection between ListField and ArrayField would be very helpful.

[rpkilby]

A very minimal docs update might be helpful here. Aside from HStoreField, JSONField and ListField don't mention their connection to their postgres counterparts. That said, I wouldn't really consider this an open concern.