nfs: new subdir Documentation/filesystems/nfs

We're adding enough nfs documentation that it may as well have its own
subdirectory.

Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/fs/cifs/export.c b/fs/cifs/export.c
index 75949d6..6177f7c 100644
--- a/fs/cifs/export.c
+++ b/fs/cifs/export.c
@@ -24,7 +24,7 @@
  */
 
  /*
-  * See Documentation/filesystems/Exporting
+  * See Documentation/filesystems/nfs/Exporting
   * and examples in fs/exportfs
   *
   * Since cifs is a network file system, an "fsid" must be included for