Add “Register elsewhere” anywhere there is a “Register” button

So people are not forced to create an account on the same host.

If I currently go to https://timbl.com/timbl/, there is a "Register" button. This button leads me to register on timbl.com (which, BTW, isn't possible in the first place because this is a single-user instance). We should probably not force people to create an account on the first host they happen to access; rather, "Register" should explain that they have a choice.

先追蹤 https://timbl.com/timbl/ 上顯示的「Register」按鈕，並找出其他 Register 按鈕共用的程式碼。檢查註冊如何在各個 host 之間選擇，然後確認每個 Register 進入點都會說明可用的選項，而不會強制在目前的 host 上註冊。