Sorry, I just found this ticket. Yes, the self-merge policy is technically documented in https://developer.lsst.io/build-ci/new_package.html :
The new package must be added to the etc/repos.yaml file in the lsstsw package along with its corresponding GitHub URL. This file is governed by a “self-merge” policy: upon opening a pull request, it will be checked by the Travis CI system, and developers may merge without further review on success. Refer to
RFC-75 for background.
But I think I can restructure that page a bit to make the process easier to follow and have policies more clearly defined. I'll take the ticket on.