📝 clarify library logger error helper routing

docs/api/library-logger-error.md

@@ -41,7 +41,7 @@ Detailed rules explaining key parameters and behaviors
 
 - This helper delegates to `error(...)` on the wrapped logger, which in turn uses `log(Level::Error, ...)`.
 - `Error` is the highest built-in severity in this sync facade API.
-- Per-call target override is not exposed here; use `log(...)` when explicit target control is required.
+- This helper does not accept a per-call target override. It uses the facade's stored target unless the facade was derived earlier with `with_target(...)` or `child(...)`.
 - Sink composition, filtering, patching, and queue wrappers still apply normally.
 - Broader composition helpers remain on the underlying `Logger[S]` and require `to_logger()` first.
 
@@ -69,6 +69,8 @@ In this example, the record carries machine-readable context without dropping to
 
 And any shared context already carried by the facade still participates through the wrapped logger pipeline.
 
+And the write still uses the facade's stored target because this shortcut does not take a one-off `target=` override.
+
 ### Error Case
 
 e.g.: