https://netplan.io/reference page redirect resulting in 404

There have been a couple of bugs in cloud-init which referenced the following URL https://netplan.io/reference.

Due to recent Diataxis migrations of content some sphinx or Readthedocs redirects may have been setup which end up forwarding the request to the url https://netplan.readthedocs.io/en/latest/netplan-yaml.html

I'm thinking the redirect should probably be https://netplan.readthedocs.io/en/latest/netplan-yaml

We may want to double check any other redirect rules in place in case something else fell through the cracks during restructuring of docs as well as checking high count 404s from Readthedocs admin reporting pages.