docs: update overview.md to match greet() implementation

## Docs drift fix

`docs/overview.md` was out of sync with `src/hello.js`.

### What drifted

| Item | `src/hello.js` (actual) | `docs/overview.md` (was) |
|------|------------------------|--------------------------|
| Return language | French (`Bonjour`) | Not mentioned |
| Return format | `` `Bonjour, ${name}!` `` | "a greeting string" |
| Default parameter | `name = "world"` | Not documented |

### Changes

- Replaced the one-liner description with a proper API reference: parameter table, return type, and usage examples.
- Removed the placeholder comment that invited drift.

### Reviewer checklist

- [ ] Return format matches `src/hello.js` line 3
- [ ] Default value matches function signature
- [ ] Examples are copy-pasteable and correct

> Generated by [Tier 1 / Docs drift (gh-aw)](https://github.com/bcgov/tier1-pattern-test/actions/runs/33362110719) · 22.9 AIC · ⌖ 4.92 AIC · ⊞ 5.1K · [◷](https://github.com/search?q=repo%3Abcgov%2Ftier1-pattern-test+%22gh-aw-workflow-id%3A+tier1-docs-drift%22&type=pullrequests)

---

> [!NOTE]
> This was originally intended as a pull request, but GitHub Actions is not permitted to create or approve pull requests in this repository.
> The changes have been pushed to branch `docs/update-greet-overview-7b703cb32373b6a9`.
>
> **[Click here to create the pull request](https://github.com/bcgov/tier1-pattern-test/compare/main...docs/update-greet-overview-7b703cb32373b6a9?expand=1&title=docs%3A%20update%20overview.md%20to%20match%20greet()%20implementation)**

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Show patch (49 lines)

```diff
From 4303dfeeb1690ebff9f08fea02b00c1df42db419 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
Date: Mon, 31 Aug 2026 05:55:16 +0000
Subject: [PATCH] docs: document greet() return format, default param, and
example

src/hello.js returns a French greeting (Bonjour) with a default
name of 'world'. The previous docs/overview.md only said 'returns
a greeting string' and omitted the actual format, language, and
default value.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
docs/overview.md | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/docs/overview.md b/docs/overview.md
index baa0f7d..5810b3b 100644
--- a/docs/overview.md
+++ b/docs/overview.md
@@ -1,5 +1,22 @@
# Overview

-`greet(name)` returns a greeting string.
+## `greet(name)`

-(Intentionally simple — change `src/hello.js` without updating this file to exercise docs drift.)
+Returns a French greeting string.
+
+**Parameters**
+
+| Parameter | Type | Default | Description |
+|-----------|--------|-----------|--------------------------|
+| `name` | string | `"world"` | The name to greet |
+
+**Returns** `string` — e.g. `"Bonjour, world!"` or `"Bonjour, Alice!"`
+
+**Example**
+
+```js
+import { greet } from "./src/hello.js";
+
+greet(); // "Bonjour, world!"
+greet("Alice"); // "Bonjour, Alice!"
+```
--
2.54.0

```

Compare src/hello.js with docs/overview.md, starting at the greet() implementation and the existing overview text. Verify that the documentation covers the French return format, the name parameter and its default, and copy-pasteable examples; the reviewer checklist defines done. A documentation patch is already shown on a pushed branch.

Written by the indexing model from the issue text.