Is `flush_every_ms` a public or private config option?

[vi]

On one hand, it is mentioned in doctest code of sled::Config, but on the other hand it is #[doc(hidden)], which sometimes suggests that it is an internal, non-semver-stable method that is pub only because of some technical reasons.

Shall it be documented properly or shall it be removed from sled::Config builder example?

[dvic]

Just wanted to ask this :)