Use conventional port (2575) in the server instantiation example

README example uses 1234 as the server port, while [Google Cloud documentation](https://docs.cloud.google.com/healthcare-api/docs/how-tos/mllp-adapter#testing_the_mllp_adapter_locally_as_a_receiver) lists 2575 as the port for the MLLP server. Any reason to use 1234 instead of (presumably) conventional port number?