📝 Add sync config export API docs

docs/api/stringify-logger-config.md

@@ -0,0 +1,99 @@
+---
+name: stringify-logger-config
+group: api
+category: config
+update-time: 20260512
+description: Serialize LoggerConfig into compact or pretty JSON text for persistence and diagnostics.
+key-word:
+    - logger
+    - config
+    - stringify
+    - public
+---
+
+## Stringify-logger-config
+
+Serialize `LoggerConfig` into JSON text. This is the easiest way to emit typed logger configuration as a string for persistence, examples, diagnostics, or generated config files.
+
+### Interface
+
+```moonbit
+pub fn stringify_logger_config(config : LoggerConfig, pretty~ : Bool = false) -> String {}
+```
+
+#### input
+
+- `config : LoggerConfig` - Config to serialize.
+- `pretty : Bool` - Whether JSON output should be pretty-printed.
+
+#### output
+
+- `String` - Serialized logger config JSON.
+
+---
+
+e.g.:
+```moonbit
+pub fn stringify_logger_config(config : LoggerConfig, pretty~ : Bool = false) -> String {}
+```
+
+#### input
+
+- `config : LoggerConfig` - Logger config value.
+- `pretty : Bool` - Pretty-print flag.
+
+#### output
+
+- `String` - JSON string.
+
+---
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- `pretty=false` produces compact JSON.
+- `pretty=true` produces indented human-readable JSON.
+- This helper builds on top of `logger_config_to_json(...)`.
+- Output is stable and suited for roundtrip config workflows.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need A Human-readable Generated Config
+
+When config should be printed or checked by humans:
+```moonbit
+println(stringify_logger_config(config, pretty=true))
+```
+
+In this example, the output is readable enough for documentation or operator inspection.
+
+#### When Need Compact Export
+
+When config should be emitted as a compact payload:
+```moonbit
+println(stringify_logger_config(config))
+```
+
+In this example, the config stays small and machine-oriented.
+
+### Error Case
+
+e.g.:
+- If callers need a JSON value rather than text, use `logger_config_to_json(...)` instead.
+
+- If config contains optional `queue=None`, the output omits that section rather than failing.
+
+### Notes
+
+Notes are here.
+
+1. This API is ideal for generated examples and stored config payloads.
+
+2. Use `pretty=true` when readability matters.
+
+3. Pair with `parse_logger_config_text(...)` for roundtrip validation workflows.
+
+4. The output describes config, not runtime sink state.