Documentation only available for "latest"
The documentation's only online version is the latest one, which apparently refers to an unreleased version of Whoosh.
For instance: http://whoosh.readthedocs.org/en/latest/facets.html refers to the Whoosh 3.0 API although it has not been released yet (https://pypi.python.org/pypi/Whoosh/).
Documentation for the latest published versions (eg. 1.x and 2.x) should be available.