Shows --port option in README

Author: flovilmart

README.md

@@ -67,6 +67,20 @@ The standalone Parse Server can be configured using [environment variables](#con
 
 Please refer to the [configuration section](#configuration) or help;
 
+To get more help for running the parse-server standalone, you can run:
+
+`$ npm start -- --help`
+
+The standalone API server supports loading a configuration file in JSON format:
+
+`$ npm start -- path/to/your/config.json`
+
+The default port is 1337, to use a different port set the `--port` option:
+
+`$ npm start -- --port=8080 path/to/your/config.json`
+
+Please refer to the [configuration section](#configuration) or help;
+
 You can also install Parse Server globally:
 
 `$ npm install -g parse-server`