Disable invitations

Even when registration is disabled, organization administrators or owners can invite users to join organization. After they are invited, they can register with the invited email even if SIGNUPS_ALLOWED is actually set to false. You can disable this functionality completely by setting INVITATIONS_ALLOWED env variable to false:

docker run -d --name bitwarden \
  -e SIGNUPS_ALLOWED=false \
  -e INVITATIONS_ALLOWED=false \
  -v /vw-data/:/data/ \
  -p 80:80 \
  vaultwarden/server:latest