I've created a new organization folder named lsst-ts (the display name is "LSST Telescope & Site" which is automatically scrapped from github). It should automatically create a job as a sub-item for are branch in a repo which contains a Jenkinsfile. (This turned out to be rather frustrating to accomplish using job-dsl and had to resort to direct xml configuration to automate.)
I have tested that the org level webhook is working as expected and newly created repos are automatically indexed. The entire org should also be reindexed once per day. However, when a repo is removed the corresponding jenkins job is not immediately removed – the webhook message for delete seems to not be handled at all. There are some configuration parameters for removing old items after X days or X number are accumulated but I'm not sure exactly what qualifies as an "old item", so I've left it at the defaults. If there is a pile up for jobs for repos that no longer exist this can be revisited.