Attached is a patch that provides a link to the catalog page for pg_db_role_settings from config.sgml. It also updates said catalog page to mention that the data from this catalog is available via psql \drds and also provides a query that will explode the setconfig column into its component parts - which \drds does not do.
I am imagine there might be a reason that the catalog pages do not reference the relevant psql meta-commands, or provide human-friendly examples, but I cannot think of what that might be and so here I provide.
David J.