doc: qualify directory read ordering for native fs

Clarify that the documented operating system directory ordering applies
to reads handled by the native file system.

Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com>
PR-URL: #65868
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: trivikr

doc/api/fs.md

@@ -7263,8 +7263,9 @@ Asynchronously read the next directory entry via readdir(3) as an
 A promise is returned that will be fulfilled with an {fs.Dirent}, or `null`
 if there are no more directory entries to read.
 
-Directory entries returned by this function are in no particular order as
-provided by the operating system's underlying directory mechanisms.
+For directory reads handled by the native file system, directory entries
+returned by this function are in no particular order as provided by the
+operating system's underlying directory mechanisms.
 Entries added or removed while iterating over the directory might not be
 included in the iteration results.