Suggestion to add the --show-deprecated option to help/docs

[stronk7]

Hi,

unless I'm missing something, the --show-deprecated option is not documented in readme / cli help. And it really would be useful to have it present there. It took some time to me to see if it was supported or no when it's important enough, IMO.

For your consideration, thanks for the estupendo linter!

Ciao :-)

[jrfnl]

Looks like it also doesn't show when using the -h argument on the command-line.

[jrfnl]

PR #84 should address this.

[jrfnl]

For the record, the --show-deprecated option was added in JakubOnderka/PHP-Parallel-Lint#94