Nightly builds / snapshots which are not formal releases must not be linked from the main download page.
Such builds have not been voted on and should only be used by developers who should be made aware that the code is without any guarantees.
Nightly builds are not formal ASF releases, and must not be promoted to the general public.
See  second para. The second sentence states:
"Do not include any links on the project website that might encourage non-developers to download and use nightly builds, snapshots, release candidates, or any other similar package."