correct maximum block size

Reference: /n/sources/patch/applied/mkpaqfsman
Date: Wed May  1 04:31:25 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/man/8/mkpaqfs	Wed May  1 04:30:08 2013
+++ /sys/man/8/mkpaqfs	Wed May  1 04:29:35 2013
@@ -35,7 +35,7 @@
 byte blocks.
 Larger blocks make large files more compact but take longer to access.
 .I Blocksize
-must be in the range of 512 bytes to 52K bytes.
+must be in the range of 512 bytes to 512K bytes.
 If the
 .B -u
 option is set, the blocks are not compressed.