The example in `numa.toml` pointed at `https://odoh-relay.numa.rs/proxy`,
but the relay only serves the ODoH endpoint at `/relay` (every other
reference in the tree — `src/config.rs` docs and tests, and
`packaging/client/numa.toml` — uses `/relay`). Users who copied the
example got `404 Not Found` on every query and SERVFAIL at the client.
Reported in #138.