doc/nodepool: update vhd-util docs

Update the docs on the package generation for the automated building
we have implemented.

Change-Id: I60816ab8686cc32b3767fc13295b95ed42e02483

doc/source/nodepool.rst

@@ -109,31 +109,9 @@ considered the next-most-recent image.
 vhd-util
 ========
 
-Creating images for Rackspace requires a patched version of vhd-util to convert
-the images into the appropriate VHD format. A package is manually managed
-at `ppa:openstack-ci-core/vhd-util` and is based on a git repo at
-https://github.com/emonty/vhd-util
-
-Updating vhd-util
------------------
-
-Should it become required to update vhd-util before Infra has a proper
-packaging repo or solution in place, one should clone from the git repo::
-
-  $ git clone git://github.com/emonty/vhd-util
-  $ cd vhd-util
-
-Then perform whatever updates and packaging work are needed. The repo is
-formatted as a git-buildpackage repo with `--pristine-tar`. When you're ready
-to upload a new verion, commit, create a source package and a tag::
-
-  $ git-buildpackage --git-tag --git-sign-tags -S
-
-This will make a source package in the parent directory. Upload it to
-launchpad::
-
-  $ cd ..
-  $ dput ppa:openstack-ci-core/vhd-util vhd-util_$version_source.changes
-
-Then probably pushing the repo to github and submitting a pull request so that
-we can keep up with the change is not a terrible idea.
+Creating images for Rackspace requires a patched version of vhd-util
+to convert the images into the appropriate VHD format.  See the
+`opendev/infra-vhd-util-deb
+<https://opendev.org/opendev/infra-vhd-util-deb>`__ for details of
+this custom package.  This is installed on a production host via a PPA
+built and published by jobs in this repository.