SNM supports DMARC reporting, but it's disabled by default. For email
greybeards, that's fine, but I think it would be useful to teach email newbies (as I was a few
months ago) that this is something you should seriously consider
enabling.
I opted to put this in a new "Advanced Configurations" section that
points experienced mailserver admins to our howto guides, and newbies to
a couple of important things.
refs: https://github.com/NixOS/infra/pull/635
To generate the list of options, we need to generate and commit a rst
file to make all files available for ReadTheDoc.
An Hydra test ensures this generated file is up-to-date. If it is not
up-to-date, the error message explains the user how to generate it:
the user just needs to run `nix-shell --run generate-rst-options`.
