document what we found in puppet

howto/postgresql.md

@@ -1204,6 +1204,14 @@ which can monitor PostgreSQL servers, but it is not deployed on all
 hosts. This is because there is still a manual step in the
 configuration of the exporter. See "installation" above.
 
+It would also be preferable if that procedure was automated in Puppet,
+but that requires haggling with the `postgresql` module which we do
+not actually use, currently. It does not directly conflict with our
+`postgres` module, but it does rewrite the `pg_hba.conf` and
+`postges.conf`. If we do eventually fix this oddity, know that we
+considered using `postgresql::server::grant`, but it might be better
+to call `postgresql_psql` directly.
+
 Note that there is a program called [pgstatsmon](https://github.com/joyent/pgstatsmon) which can provide
 very detailed information about the state of a PostgreSQL database,
 see [this blog post for details](https://www.davepacheco.net/blog/2019/visualizing-postgresql-vacuum-progress/).