📝 Add sync config export API docs

docs/api/logger-config-to-json.md

@@ -0,0 +1,97 @@
+---
+name: logger-config-to-json
+group: api
+category: config
+update-time: 20260512
+description: Convert LoggerConfig into a JSON value for export, persistence, or generated config output.
+key-word:
+    - logger
+    - config
+    - json
+    - public
+---
+
+## Logger-config-to-json
+
+Convert a typed `LoggerConfig` into a `JsonValue`. This helper is the structured export path when config should be persisted, inspected, or embedded into larger JSON payloads.
+
+### Interface
+
+```moonbit
+pub fn logger_config_to_json(config : LoggerConfig) -> @json_parser.JsonValue {}
+```
+
+#### input
+
+- `config : LoggerConfig` - Typed logger configuration.
+
+#### output
+
+- `JsonValue` - JSON representation of the logger config.
+
+---
+
+e.g.:
+```moonbit
+pub fn logger_config_to_json(config : LoggerConfig) -> @json_parser.JsonValue {}
+```
+
+#### input
+
+- `config : LoggerConfig` - Config to export.
+
+#### output
+
+- `JsonValue` - Structured JSON value.
+
+---
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- The output includes `min_level`, `target`, `timestamp`, `sink`, and optional `queue`.
+- Sink export is delegated to `sink_config_to_json(...)`.
+- The result is suitable for downstream JSON composition as well as stringification.
+- Exported JSON follows the stable supported config schema rather than raw internal runtime state.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need Generated Config Output
+
+When code constructs config and later exports it:
+```moonbit
+let json = logger_config_to_json(LoggerConfig::new(target="svc"))
+```
+
+In this example, the typed config becomes a structured JSON value.
+
+#### When Need To Embed Logger Config In A Larger Payload
+
+When logger config should be one part of a bigger object:
+```moonbit
+let payload = logger_config_to_json(config)
+```
+
+In this example, the helper avoids re-implementing config serialization by hand.
+
+### Error Case
+
+e.g.:
+- If `queue` is `None`, the exported JSON simply omits the queue field.
+
+- If some sink options are unused by the chosen sink kind, they still follow the supported config export shape rather than a runtime-only interpretation.
+
+### Notes
+
+Notes are here.
+
+1. Use this API when you need a JSON value instead of text output.
+
+2. Use `stringify_logger_config(...)` for immediate string output.
+
+3. This helper complements `parse_logger_config_text(...)` for roundtrip workflows.
+
+4. The output is configuration-oriented, not runtime-state-oriented.