Improve description of logical path

[jmooring]

https://discourse.gohugo.io/t/ref-not-working-when-using-relative-path-since-v0-123-0/48939/13

The desired language here would be "node" and "tree", consistent with language commonly used to describe data structures. Unfortunately, we already defined "node" to exclude regular pages via Page.IsNode. If we deprecate that we can begin using language such as:

The logical path is the path between two nodes, either relative to each other or absolute from the root of the tree.

Wait and see what happens with gohugoio/hugo#11574.