wrote a man page & included in package for install

Hi!

I installed this package recently, and was trying to figure out how to use it. The first thing I did was check `man jslint` and was disappointed to have none found. Then I ran `jslint --help` which spit out a long usage string but didn't explain any of the options! After trying a few other invocations (info, -h) I pulled up the source and was happily surprised to see the options clearly documented there at the top of the file. That said - I'd like to spare anyone else from the confusion, and so I wrote a man page with excerpts from the inline comments and the README. I included it in the package.json to install with the package. Then I tested the install and everything went smoothly.

There might be a better way to do this - it will have to be upkept - perhaps there is a way to generate this file automatically. But it's pretty simple, so I think that this will be a good addition right now.

Let me know what you think!
Thanks