📝 Align API docs with updated interface template

docs/api/fields.md

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+---
+name: fields
+group: api
+category: record
+update-time: 20260512
+description: Build structured field arrays ergonomically from key-value tuples.
+key-word:
+    - fields
+    - record
+    - helper
+    - public
+---
+
+## Fields
+
+Create an `Array[Field]` from an array of `(String, String)` tuples. This helper reduces repetitive `field(...)` calls when binding context or constructing event fields.
+
+### Interface
+
+```moonbit
+pub fn fields(entries : Array[(String, String)]) -> Array[Field] {}
+```
+
+#### input
+
+- `entries : Array[(String, String)]` - Tuple entries where `.0` is the field key and `.1` is the field value.
+
+#### output
+
+- `Array[Field]` - Structured field array ready for logger APIs.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- Each tuple becomes one `Field` value.
+- Order is preserved.
+- This helper is purely ergonomic and does not add validation beyond normal string handling.
+- It is commonly used with `bind(...)`, `with_context_fields(...)`, and per-event field arguments.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Build Reusable Context Fields
+
+When binding stable metadata to a logger:
+```moonbit
+let logger = Logger::new(console_sink(), target="audit")
+  .bind(fields([("service", "billing"), ("scope", "login")]))
+```
+
+In this example, tuple syntax is shorter and easier to scan than repeated `field(...)` calls.
+
+#### When Build Small Per-event Field Arrays
+
+When logging a few fields inline:
+```moonbit
+logger.info("accepted", fields=fields([("user", "alice"), ("status", "ok")]))
+```
+
+In this example, the helper keeps call sites compact.
+
+### Error Case
+
+e.g.:
+- If `entries` is empty, the result is just an empty field array.
+
+- Duplicate keys are preserved rather than collapsed.
+
+### Notes
+
+Notes are here.
+
+1. Use `field(...)` when only one field is needed.
+
+2. Use `fields(...)` when tuple syntax improves readability.
+
+3. This helper preserves order.
+
+4. No special deduplication or normalization is performed.