Refine usage.

trunk/src/app/srs_app_config.cpp

@@ -3436,13 +3436,13 @@ void SrsConfig::print_help(char** argv)
            RTMP_SIG_SRS_SERVER ", " RTMP_SIG_SRS_URL ", licensed under " RTMP_SIG_SRS_LICENSE
            ", built at " SRS_AUTO_BUILD_DATE ", configured by " SRS_AUTO_USER_CONFIGURE
            ", which means " SRS_AUTO_CONFIGURE "\n""\n"
-           "Usage: %s [-h?vVgG] [[-t] -c <filename>]\n"
+           "Usage: %s <-h?vVgG>|<[-t] -c filename>\n"
            "Options:\n"
-           "   -?, -h              : show this help and exit(0)\n"
-           "   -v, -V              : show version and exit(0)\n"
-           "   -g, -G              : show server signature and exit(0)\n"
-           "   -t                  : test configuration file, exit(error_code).\n"
-           "   -c filename         : use configuration file for SRS\n"
+           "   -?, -h              : Show this help and exit 0.\n"
+           "   -v, -V              : Show version and exit 0.\n"
+           "   -g, -G              : Show server signature and exit 0.\n"
+           "   -t                  : Test configuration file, exit with error code(0 for success).\n"
+           "   -c filename         : Use config file to start server.\n"
            "For example:\n"
            "   %s -v\n"
            "   %s -t -c " SRS_CONF_DEFAULT_COFNIG_FILE "\n"