Add '-ts' options to zconfig.sh/zfault.sh usage

When adding this functionality originally the options to only
run specific tests (-t), or conversely skip specific tests (-s)
were omitted from the usage page.  This commit adds the missing
documentation.

scripts/zconfig.sh

@@ -16,7 +16,7 @@ PROG=zconfig.sh
 usage() {
 cat << EOF
 USAGE:
-$0 [hvc]
+$0 [hvcts]
 
 DESCRIPTION:
 	ZFS/ZPOOL configuration tests
@@ -25,6 +25,8 @@ OPTIONS:
 	-h      Show this message
 	-v      Verbose
 	-c      Cleanup lo+file devices at start
+	-t <#>  Run listed tests
+	-s <#>  Skip listed tests
 
 EOF
 }

scripts/zfault.sh

@@ -42,7 +42,7 @@ PROG=zfault.sh
 usage() {
 cat << EOF
 USAGE:
-$0 [hvc]
+$0 [hvcts]
 
 DESCRIPTION:
 	ZPOOL fault verification tests