Option to create custom output file name

[voronianski]

This will be very helpful.. for example getting file name from title (like it's already done - https://github.com/jashkenas/docco/blob/master/docco.js#L146) or from cli option.

[keithamus]

Great idea @voronianski and thanks for the time making this issue. Do you fancy changing the code and making a PR? You just need to edit this file and doing so gets you on the list of contributors; neat!

[voronianski]

@keithamus check my PR 😉