doc(fs): clarify glob pattern examples per review feedback

Add note about +(spec|test) pattern matching behavior and provide
more precise alternative using brace expansion. Also clarify that
returned paths use forward slashes and are relative to cwd.

Refs: #58988

Author: mag123c

doc/api/fs.md

@@ -1149,6 +1149,11 @@ for await (const entry of glob('src/{components,utils}/**/*.js'))
 // Extended glob patterns
 for await (const entry of glob('test/**/*.+(spec|test).js'))
   console.log(entry); // Test files ending with .spec.js or .test.js
+  // Note: This also matches files like 'foo.spectest.js'
+
+// More precise pattern using brace expansion
+for await (const entry of glob('test/**/*.{spec,test}.js'))
+  console.log(entry); // Only matches .spec.js or .test.js files
 
 // Excluding patterns
 for await (const entry of glob('**/*.js', { exclude: ['node_modules/**'] }))
@@ -1174,6 +1179,9 @@ const { glob } = require('node:fs/promises');
   case-sensitive on other platforms
 * **Path separators**: Forward slashes (`/`) are used in patterns regardless of
   platform; they are automatically converted to the appropriate separator
+* **Returned paths**: Results always use forward slashes (`/`) as path separators,
+  even on Windows. Paths are relative to `options.cwd` if provided, otherwise
+  relative to the current working directory
 * **Symlinks**: Symbolic links are followed and their targets are included in results
 * **Hidden files**: Files starting with `.` are included in results when explicitly
   matched, but not when using `*` or `**` patterns