Why isn't sslmode=no-verify documented anywhere?

### Summary

I had to dig everywhere through your repo to find a closed issue that stated I should use `?sslmode=no-verify` at the end of my connection string for a hosted PostgreSQL that uses self-signed certificates.

I literally do not have this problem with any other library, so apparently PostGraphile requires SSL verify by default. This is not documented anywhere, nor is it documented how to override it.

I just literally tried out your library today, and it's a great idea, but people will be turned off by lack of documentation and having to dig through library source to figure out what is going on with something so basic that does not present a problem with psql, pgcli, or other library tools (unless the user explicitly specifies they want SSL verification).

It's a great project, but a huge opportunity is missed by not having something very basic like this documented. It's not in the CLI help or args. If designed for postgres, honestly it should work out of the box with the same environment variables and settings that work with psql, pgcli, etc. Large enterprises that would want to use this with extra security (probably not required in most cloud/k8s environments as they are all heavily firewalled by default), their environment vars would call for verification anyway.

Please add docs for this, at the very beginning where people are trying to start it up. Literally would take maybe one line of documentation in the README, and SSL modes mentioned in 5-10 lines in the actual docs.

Otherwise, now that I can connect, I'm looking forward to trying this out and saving me huge headaches I've had trying out another library. I can already tell this has great documentation, just trying to get started.

Thank you.