An unqualified `[`open_or_create`]` in the module-level doc does not
resolve once the `kv` feature is on, which is the only configuration
where the module is compiled at all — so `docs-rustdoc` failed in CI
while a default-feature `cargo doc` passed locally. Measured both ways:
kv off documents clean, kv on errors `no item named open_or_create in
scope`.
Qualifying the path fixes it without widening any visibility, which is
the rule that check exists to protect.
b8e19a31b2