message: Improve osvr_server help
diff: @@ -62,7 +62,8 @@ int main(int argc, char *argv[]) {
  optionsPositional.add("config", -1);
  // clang-format off
  optionsVisible.add_options()
  - ("config", opt::value<std::vector<std::string> >(), "server configuration filename")
  + ("config", opt::value<std::vector<std::string> >(),
  + "server configuration filename (can also pass without a flag as a positional option)")
  ("help,h", "display this help message")
  ("verbose,v", "enable verbose logging")
  ("debug,d", "enable debug logging");
  