tc: improve filter help texts a bit

This fixes a few syntax errors and changes route filter help text to use
classid instead of flowid to be consistent with other filters' help
texts.

Signed-off-by: Phil Sutter <phil@nwl.cc>
diff --git a/tc/f_rsvp.c b/tc/f_rsvp.c
index cb7b8fb..1fe9b15 100644
--- a/tc/f_rsvp.c
+++ b/tc/f_rsvp.c
@@ -27,7 +27,7 @@
 static void explain(void)
 {
 	fprintf(stderr, "Usage: ... rsvp ipproto PROTOCOL session DST[/PORT | GPI ]\n");
-	fprintf(stderr, "                [ sender SRC[/PORT | GPI ]\n");
+	fprintf(stderr, "                [ sender SRC[/PORT | GPI ] ]\n");
 	fprintf(stderr, "                [ classid CLASSID ] [ action ACTION_SPEC ]\n");
 	fprintf(stderr, "                [ tunnelid ID ] [ tunnel ID skip NUMBER ]\n");
 	fprintf(stderr, "Where: GPI := { flowlabel NUMBER | spi/ah SPI | spi/esp SPI |\n");