hush: implement "hush -s"

function                                             old     new   delta
hush_main                                           1015    1031     +16
packed_usage                                       32757   32745     -12
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 16/-12)              Total: 4 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash.c b/shell/ash.c
index 5586015..56fba4a 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -13948,7 +13948,7 @@
 
 
 //usage:#define ash_trivial_usage
-//usage:	"[-/+OPTIONS] [-/+o OPT]... [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS]]"
+//usage:	"[-/+OPTIONS] [-/+o OPT]... [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS] / -s [ARGS]]"
 //usage:#define ash_full_usage "\n\n"
 //usage:	"Unix shell interpreter"