[doc/io] Sync Directory.rename()/renameSync()

Change-Id: Iff214619ceda27a0dfd768d515a4dcab250b9eb9
CoreLibraryReviewExempt: Documentation-only change
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/327521
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Brian Quinlan <bquinlan@google.com>
diff --git a/sdk/lib/io/directory.dart b/sdk/lib/io/directory.dart
index bd478a5..07e77d0 100644
--- a/sdk/lib/io/directory.dart
+++ b/sdk/lib/io/directory.dart
@@ -239,7 +239,7 @@
   /// systems, if [newPath] identifies an existing empty directory then that
   /// directory is deleted before this directory is renamed.
   ///
-  /// If [newPath] identifies an existing file, the operation
+  /// If [newPath] identifies an existing file or link, the operation
   /// fails and the future completes with a [FileSystemException].
   Future<Directory> rename(String newPath);