ext4: correct documentation for grpid mount option

The grpid option is currently described as being the same as nogrpid.

Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 75236c0..d081ce0 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -233,7 +233,7 @@
 data_err=abort		Abort the journal if an error occurs in a file
 			data buffer in ordered mode.
 
-grpid			Give objects the same group ID as their creator.
+grpid			New objects have the group ID of their parent.
 bsdgroups
 
 nogrpid		(*)	New objects have the group ID of their creator.