Fix spelling error in manpage.

Author: Chris Taylor <ctaylor@debian.org>
--- a/man/scrub.1.in
+++ b/man/scrub.1.in
@@ -156,7 +156,7 @@ The
 .I "dod"
 .B scrub
 sequence is compliant with the DoD 5220.22-M procedure for sanitizing 
-removeable and non-removeable rigid disks which requires overwriting
+removable and non-removable rigid disks which requires overwriting
 all addressable locations with a character, its complement, then a random
 character, and verify.  
 Please refer to the DoD document for additional constraints.
