Ignore `build.js` and markdown files in `.npmignore`

[jonschlinkert]

To exclude build-related files from the published package. I'd be happy to do a pr.

Thanks!

[TooTallNate]

Thanks, but there are no build files in this module.

[TooTallNate]

Oh I see, you mean the build.js file. I'd rather use .npmignore I think. PR welcome!

[jonschlinkert]

I though build.js, set.js and hash.js were all build related? It's not a big deal you can close this, I don't have a lot of time to do prs atm.