We used to maintain docs about the puppetdb.conf file in the Puppet reference manual, at e.g. https://docs.puppetlabs.com/puppet/latest/reference/config_file_puppetdb.html. Ryan Senior moved the canonical version of this documentation into the puppetdb repo, and PuppetDB 3.0 will be the first version to release with that file present in the docs.
Right now, we're linking to that file using "master" as the URL segment, because master is excluded from the "latest" alias. Once there's a numbered version with that file present, we should change "master" to "latest" anywhere that file is linked in the Puppet docs proper.
This commit shows where the link was added: https://docs.puppetlabs.com/puppet/3.7/reference/config_file_puppetdb.html
We'll need to change the most recent Puppet 4.x docs (4.2 at the time of this writing).