How to setup multiple instances on one server?

Preliminary docs. These are the relevant config values. And maybe there's some typo below — can you please wait with trying this?, until I've tested myself, maybe tomorrow or during the weekend. Then I'll notify you when i know this works. I'm posting this now anyway, though, in case you're curious, or maybe you want to have a look and ask something.

## This is the main website. Here you can login as super admin, to view events from all your sites hosted by that server.
talkyard.hostname="talkyard.yourdomain.com"

## To become owner of the main website, during installation.
talkyard.becomeOwnerEmailAddress="your@email.address"

## When you create new forums, they will be placed at this domain,
## example:  the-2nd-forum.yourdomain.com
## Consider getting a wildcard cert from Let'sEncrypt.
talkyard.baseDomain="yourdomain.com"

## When you configure Google OpenAuth apps, you currently do that only once
## for all forums on the whole server. People get redirected to this address,
## for logging in:
## (You can leave it commented out — then, the `talkyard.hostname` setting gets used instead.)
# talkyard.loginOrigin="https://talkyard.yourdomain.com"

## To create new forums, people need to go to the below address,
## and url pathname  /-/create-site
## example:  http(s)://talkyard.yourdomain.com/-/create-site
talkyard.createSiteHostname="talkyard.yourdomain.com"

## To create a *test* site, they need to go to this address:
## and url pathname  /-/create-test-site
## example:  http(s)://talkyard.yourdomain.com/-/create-test-site
#talkyard.createTestSiteHostname="talkyard.yourdomain.com"

#talkyard.superAdmin.emailAddresses="your@email.address"