prune-packed: add -q to usage

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/builtin-prune-packed.c b/builtin-prune-packed.c
index a57b76d..9777300 100644
--- a/builtin-prune-packed.c
+++ b/builtin-prune-packed.c
@@ -2,7 +2,7 @@
 #include "cache.h"
 
 static const char prune_packed_usage[] =
-"git-prune-packed [-n]";
+"git-prune-packed [-n] [-q]";
 
 #define DRY_RUN 01
 #define VERBOSE 02