Updated website docs and /twenty-server/.env (#8801)

Fix for the issue Incorrect Database Connection String in .env File
#8741

---------

Co-authored-by: Félix Malfait <felix@twenty.com>

packages/twenty-docker/k8s/manifests/deployment-db.yaml

@@ -33,7 +33,7 @@ spec:
             - name: PGUSER_SUPERUSER
               value: "postgres"
             - name: PGPASSWORD_SUPERUSER
-              value: "twenty"
+              value: "postgres"
           ports:
             - containerPort: 5432
               name: tcp