Revert "updated readme to explain potential breaking config change"

This reverts commit 379c7a5ed0bcc97b036ab599b246c130589f571b.

Because really there is no BC break and the new value don't load resemble.js neither resemble container

https://github.com/Huddle/PhantomCSS/blob/master/phantomcss.js#L92 Append `node_modules` twice.
`path = [root,'node_modules','resemblejs','resemble.js'].join(fs.separator);`

Then `resemblejscontainer.html` cannot be loaded too because try to find it inside of `node_modules` folder
https://github.com/Huddle/PhantomCSS/blob/master/phantomcss.js#L54
`_resembleContainerPath = (options.libraryRoot || '.') + fs.separator + 'resemblejscontainer.html'`