Fix availability of the Node doc at the root URL
Fix availability of the Node doc at the root URL

As a shortcut, we make the Node document available right under the API
version tag, e.g. http://host/mn/v1. When support for the v2 version tag
in the URL was added, this stopped working, making the Node doc only
available at http://host/mn/v1/node.

DataONEorg/d1_python,DataONEorg/d1_python,DataONEorg/d1_python,DataONEorg/d1_python