Here are a few things we need to change/confirm about the sqre/infrastructure/documenteer job:
1. We need to be able to set a list of Git Refs of packages to checkout. This is important so that developers can build/test their documentation before merging tickets. That is, I think the job needs to look like `stack-os-matrix`. (The git ref passed to ltd-mason will be based on this text, so that development builds appear as pipelines.lsst.io/v/(slug) editions.
2. We need to let a user set the git ref of the `pipelines_lsst_io` repo as well. Ideally this would come from the list of git refs in (1), but it could be a separate text entry initially.
3. The version of `documenteer` that's installed needs to come from the version of documenteer listed in `pipelines_lsst_io`'s requirements.txt file. I really need this dependency to be established though the documentation repo, rather than from an external Jenkins job. Otherwise, it’ll be hard for me to upgrade Sphinx extensions and the theme while also maintaining maintenance branches of documentation.