Documentation/admin-guide: xfs: drop doubled word

Drop the doubled word "for".

Signed-off-by: Randy Dunlap <[e-mail]>
Reviewed-by: Darrick J. Wong <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: [e-mail]
Cc: Darrick J. Wong <[e-mail]>
Cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/admin-guide/xfs.rst

···
 	logbsize must be an integer multiple of the log
 	stripe unit configured at **mkfs(8)** time.
 
-	The default value for for version 1 logs is 32768, while the
+	The default value for version 1 logs is 32768, while the
 	default value for version 2 logs is MAX(32768, log_sunit).
 
   logdev=device and rtdev=device