Incorrect vendor paths for different folder levels

The require statement in `index.php` and the `nut` symlink point to the wrong location if the paths configured are different than one level deep. Such as `sites/mysite.com/public`.

Inspect the require statement in index.php and the nut symlink, then reproduce the setup with a path such as sites/mysite.com/public. Trace how each path is assembled for different folder depths. Done means both locations resolve the vendor directory correctly regardless of the configured path depth.

Written by the indexing model from the issue text.