docs: ABI: Fix the spelling oustanding to outstanding in the file sysfs-fs-xfs

s/oustanding/outstanding/
Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Documentation/ABI/testing/sysfs-fs-xfs

@@ -33,7 +33,7 @@ Contact:	xfs@oss.sgi.com
 Description:
 		The current state of the log write grant head. It
 		represents the total log reservation of all currently
-		oustanding transactions, including regrants due to
+		outstanding transactions, including regrants due to
 		rolling transactions. The grant head is exported in
 		"cycle:bytes" format.
 Users:		xfstests