added more informationabout BPF to --help

Author: =

hcxdumptool.c

@@ -5227,6 +5227,9 @@ fprintf(stdout, "%s %s  (C) %s ZeroBeat\n"
 	"Berkeley Packet Filter:\n"
 	"-----------------------\n"
 	"  see man bpfc\n"
+	"  see docs/example.md\n"
+	"  see https://docs.kernel.org/bpf\n"
+	"Always check your filter settings with tshark before starting an attack!\n"
 	"\n"
 	"Important recommendation:\n"
 	"-------------------------\n"