correct typo

Reference: /n/atom/patch/applied/mkpaqfstypo
Date: Thu Jun 12 05:14:28 CES 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/paqfs/mkpaqfs.c	Thu Jun 12 05:14:21 2014
+++ /sys/src/cmd/paqfs/mkpaqfs.c	Thu Jun 12 05:14:22 2014
@@ -67,7 +67,7 @@
 				blocksize *= 1024;
 		}
 		if(blocksize < MinBlockSize)
-			sysfatal("blocksize too small: must be at lease %d", MinBlockSize);
+			sysfatal("blocksize too small: must be at least %d", MinBlockSize);
 		if(blocksize > MaxBlockSize)
 			sysfatal("blocksize too large: must be no greater than %d", MaxBlockSize);
 		break;