added reference to pcapng file format
@@ -8288,6 +8288,7 @@ fprintf(stdout, "%s %s (C) %s ZeroBeat\n"
" it is mandatory that the driver support ioctl() system calls, monitor mode and full packet injection!\n"
"-o <dump file> : output file in pcapng format, filename '-' outputs to stdout, '+' outputs to client\n"
" including radiotap header (LINKTYPE_IEEE802_11_RADIOTAP)\n"
+ " (reference: https://github.com/pcapng/pcapng)\n"
"-f <frames> : frames to save\n"
" bitmask:\n"
" 0: clear default values\n"
