Fix arguments for set_password in help string.

src/ziptool.c

diff --git a/src/ziptool.c b/src/ziptool.c
index f647adc..b33fc0c 100644
--- a/src/ziptool.c
+++ b/src/ziptool.c
@@ -862,7 +862,7 @@
     { "set_file_comment", 2, "index comment", "set file comment", set_file_comment },
     { "set_file_compression", 3, "index method flags", "set file compression method", set_file_compression },
     { "set_file_mtime", 2, "index timestamp", "set file modification time", set_file_mtime },
-    { "set_password", 1, "set default password", "set default password for encryption", set_password },
+    { "set_password", 1, "password", "set default password for encryption", set_password },
     { "stat", 1, "index", "print information about entry", zstat },
     { "unchange_all", 0, "", "revert all changes", unchange_all },
     { "zin_close", 1, "index", "close input zip_source (for internal tests)", zin_close }