.. note::
Dropping support for Elasticsearch versions prior 6.x. This is unfortunate,
but this project depends on the upstream ``django-elasticsearch-dsl`` where
as of version 6.4.x the support for older Elasticsearch versions was
dropped. Use ``django-elasticsearch-dsl-drf`` version 0.18 if you need
to work with 5.x or 2.x.
- Dropping support for Elasticsearch versions prior to 6.x.