When using `fs.watch()` with `recursive: true`, the callback receives a
relative path from the watched directory (e.g., `'subdir/file.txt'`),
not just a filename.
Renaming the parameter from `filename` to `relativePath` makes this
behavior immediately clear to developers.
**Before:**
```ts
(event, filename) => {
console.log(`Detected ${event} in ${filename}`);
}
```
**After:**
```ts
(event, relativePath) => {
console.log(`Detected ${event} in ${relativePath}`);
}
```
This is a documentation-only change that improves clarity without
altering any functionality.
Co-authored-by: Braden Wong <git@bradenwong.com>
