Mention -x in usage.

diff --git a/main.c b/main.c
index 805957badef0a72246b34f495a7ec63861e70988..f81790e3d43a9538c55c5f332799e1b45c617baf 100644 (file)
--- a/main.c
+++ b/main.c
@@ -46,6 +46,7 @@ usage(const char *pname)
 "      -r              Process route information\n"
 "      -t              Process track information\n"
 "      -w              Process waypoint information [default]\n"
+"      -x filtername   Invoke filter\n"
 "      -D level        Set debug level [%d]\n"
 "\n"
 "File Types (-i and -o options):\n"