Bundle path is /vendor/bundle not vendor/bundler

Small typo, but when I was reading the `bundler config` docs I was confused since I thought it was `vendor/bundle`, at least according to this code: https://github.com/carlhuda/bundler/blob/master/lib/bundler/cli.rb#L216
Merge pull request #36 from kamui/patch-1

Bundle path is /vendor/bundle not vendor/bundler