📝 Update More API Document

docs/api/default-sink-config.md

@@ -0,0 +1,60 @@
+---
+name: default-sink-config
+group: api
+category: config
+update-time: 20260520
+description: Create the default SinkConfig used by logger config helpers.
+key-word:
+    - sink
+    - config
+    - default
+    - public
+---
+
+## Default-sink-config
+
+Create the default `SinkConfig` used by logger config helpers. This helper is useful when callers want the library's baseline sink config value explicitly.
+
+### Interface
+
+```moonbit
+pub fn default_sink_config() -> SinkConfig {
+```
+
+#### output
+
+- `SinkConfig` - Default sink config value.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- This helper returns the same baseline sink config used by `LoggerConfig::new(...)` defaults.
+- The default sink config is console-oriented unless later replaced by explicit config composition.
+- It is a typed config object, not a runtime sink instance.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need An Explicit Baseline Sink Config
+
+When config assembly wants the default sink as a concrete value:
+```moonbit
+let sink = default_sink_config()
+```
+
+In this example, the baseline sink config can be reused or embedded explicitly.
+
+### Error Case
+
+e.g.:
+- There is no failure path for retrieving the default sink config.
+
+- If a real sink instance is required for direct `Logger::new(...)` code paths, use a sink constructor such as `console_sink()` instead.
+
+### Notes
+
+1. This helper is for config-driven assembly, not runtime sink wiring.
+
+2. It is most useful in explicit config composition code.