Update docker cmd-line in Getting Started

[marcogario]

The example imposters in the Getting Started page use ports 4545 and 5555 . The docker container is not exposing them but 8080. AFAIU 8080 is not used in anyway, and only the controller at 2525 needs to be additionally exposed.

The file imposters.ejs does not seem to exist in the container, but I believe it is not necessary for these examples either, so I am removing it. For reference, the error was:

$ docker run --rm -p 2525:2525 -p 8080:8080 bbyars/mountebank:2.6.0 mb start --configfile imposters.ejs
info: [mb:2525] mountebank v2.6.0 now taking orders - point your browser to http://localhost:2525/ for help
No such file: imposters.ejs
Error: ENOENT: no such file or directory, open 'imposters.ejs'
    at Object.openSync (fs.js:497:3)
    at Object.readFileSync (fs.js:393:35)
    at Object.load (/usr/local/lib/node_modules/mountebank/node_modules/mountebank-formatters/src/default.js:41:29)
    at Object.load (/usr/local/lib/node_modules/mountebank/node_modules/mountebank-formatters/src/index.js:13:43)
    at Object.loadConfig (/usr/local/lib/node_modules/mountebank/src/cli/api.js:70:43)
    at Object.start (/usr/local/lib/node_modules/mountebank/bin/mb:48:23)
    at processTicksAndRejections (internal/process/task_queues.js:95:5) {
  errno: -2,
  syscall: 'open',
  code: 'ENOENT',
  path: 'imposters.ejs'
}

[bbyars]

Good catch, thanks!