///
/// If the map did not have this key present, `None` is returned.
///
- /// If the map did have this key present, the key is not updated, the
- /// value is updated and the old value is returned.
- /// See the [module-level documentation] for more.
+ /// If the map did have this key present, the value is updated, and the old
+ /// value is returned. The key is not updated, though; this matters for
+ /// types that can be `==` without being identical. See the [module-level
+ /// documentation] for more.
///
/// [module-level documentation]: index.html#insert-and-complex-keys
///