Update reporter usage w/ missing reporter

[mariozig]

A few months ago i added a new reporter: #27

Unfortunately i forgot to update the reporter's help text! This PR just updates the usage description for the --reporter option.

Thanks!

[ecamacho]

@mariozig thank you! I noticed this the other day because I'm using your reporter in some scripts and I couldn't find the help about it. I had to dig in the code.

[mariozig]

Ewww code! hahah

Thanks for approving. Is this something you'd cut another release for or just keep in the queue? Asking bc i want to make sure i update mariozig/homebrew-public@88ba90b if a new version is coming.