Sets composer.json config to use typo3 cms in vendor directory

composer.json

@@ -54,7 +54,8 @@
   },
   "extra": {
     "typo3/cms": {
-      "web-dir": "html"
+      "web-dir": "html",
+      "cms-package-dir": "{$vendor-dir}/typo3/cms"
     },
     "helhum/typo3-console": {
       "install-binary": true,