TYPO3 Core

The new composer installer now features the possibility to specify the path of the document root
and also the path of the typo3/cms package

It can be specified in the extra section of your composer root package like that:

"extra": {
    "typo3/cms": {
        "cms-package-dir": "{$vendor-dir}/typo3/cms",
        "web-dir": "web" 
    },
}