Changed 'blocks' to 'usage' because we may not be getting quotas from

a ufs filesystem and it may be reporting in K instead of 512b blocks.
This is true when using a vxfs filesystem (on a solaris box) for instance.

PR:	bin/14545
Submitted by:	Jim Pirzyk
Reviewed by:	jkh
MFC after:	1 week

usr.bin/quota/quota.c

@@ -403,7 +403,7 @@ heading(type, id, name, tag)
 	if (!qflag && tag[0] == '\0') {
 		printf("%15s%8s %7s%8s%8s%8s %7s%8s%8s\n"
 			, "Filesystem"
-			, "blocks"
+			, "usage"
 			, "quota"
 			, "limit"
 			, "grace"