message: Clarify matrix configurations
diff: @@ -85,7 +85,8 @@ auto input_format =
  " \"num_blocks\": <num-blocks>,\n"
  " \"block_size\": <block-size>\n"
  " }\n"
  - " }\n"
  + " },\n"
  + " ...\n"
  " ]\n"
  " <output-file> is a string specifying a path to the output file\n"
  " <matrix-type> is a string specifying the type of matrix to generate,\n"
  @@ -129,9 +130,9 @@ void initialize_argument_parsing(int *argc, char **argv[])
  std::ostringstream doc;
  doc << "A utility that generates various types of matrices.\n"
  << "Usage: " << (*argv)[0] << " [options]\n"
  - << " The standard input should contain a list of matrix\n"
  - << " configurations in the following format:" << input_format
  - << std::endl;
  + << " The standard input should contain a JSON array of matrix\n"
  + << " configurations in the following format:\n"
  + << input_format << std::endl;
  gflags::SetUsageMessage(doc.str());
  std::ostringstream ver;
  