For marketing purposes do I maintain one identical website with two different domains, in TYPO3 v8 I would simply add a domain record on the root page and TYPO3 would take care of the rest with respect to the requested domain (perhaps only a conditional base URL with Typoscript, and a personalised robots.txt for each site trough realurl) ...
With v9 I cannot find a way to do this, I tried to enter a second site definition with yaml manually, but the second one simply does not show up ...