📝 Add configured logger file state API docs

docs/api/configured-logger-file-reset-failure-counters.md

@@ -0,0 +1,75 @@
+---
+name: configured-logger-file-reset-failure-counters
+group: api
+category: runtime
+update-time: 20260512
+description: Reset the file failure counters recorded by the configured runtime file sink.
+key-word:
+    - logger
+    - runtime
+    - file
+    - public
+---
+
+## Configured-logger-file-reset-failure-counters
+
+Reset the file failure counters recorded by a `ConfiguredLogger`. This helper clears open, write, flush, and rotation failure metrics together.
+
+### Interface
+
+```moonbit
+pub fn ConfiguredLogger::file_reset_failure_counters(self : ConfiguredLogger) -> Bool {}
+```
+
+#### input
+
+- `self : ConfiguredLogger` - Config-driven runtime logger whose file failure counters should be cleared.
+
+#### output
+
+- `Bool` - Whether the reset was applied.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- File-backed sinks clear all file failure counters together.
+- Queued file sinks forward the reset behavior to the wrapped file sink.
+- Non-file sinks return `false`.
+- This helper is useful after diagnostics, recovery, or controlled tests.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need A Fresh Diagnostics Baseline
+
+When previous failure history should be cleared before a new observation window:
+```moonbit
+ignore(logger.file_reset_failure_counters())
+```
+
+In this example, future failures can be measured from a clean baseline.
+
+#### When Validate Post-recovery Behavior
+
+When recovery logic should clear old counters before rechecking health:
+```moonbit
+ignore(logger.file_reset_failure_counters())
+ignore(logger.file_open_failures())
+```
+
+In this example, the configured logger starts a new diagnostics window after reset.
+
+### Error Case
+
+e.g.:
+- If the configured sink is not file-backed, the method returns `false`.
+
+- If callers need the current values before clearing them, they should read the counters or `file_state()` first.
+
+### Notes
+
+1. Use this helper after diagnostics or recovery, not before capturing needed evidence.
+
+2. It is the reset companion for the file failure-counter helpers.