I think the README.rst might be out of date for Haystack 2.x.
This part:
Alter all of your SearchIndex subclasses to inherit from queued_search.indexes.QueuedSearchIndex (as well as indexes.Indexable).
should maybe read:
In your settings.py:
HAYSTACK_SIGNAL_PROCESSOR = 'queued_search.signals.QueuedSignalProcessor'