message: fix misspelled words in client.py help message
diff: @@ -233,7 +233,7 @@ if __name__ == "__main__":
  "--headers",
  dest="headers",
  metavar="KEY=VALUE[,KEY=VALUE]",
  - help="list of comma-delimited, key value pairs to include as tranport headers.",
  + help="list of comma-delimited, key value pairs to include as transport headers.",
  )
  cfg = parser.parse_args()
  