Add sign-up info

app/register/page.tsx

@@ -139,6 +139,10 @@ function RegisterComponent() {
         ) : (
           <div>
             <div>
+              <h2 className="mt-6 text-center text-xl font-extrabold text-red-700">
+                The project is still in development, you can still sign up if you want to test it, but your account
+                may be deleted at any time. To get release updates, fill in this <a href='https://forms.gle/tKnXUMAbEreMK6FC6'>form</a>.
+              </h2>
               <h2 className="mt-6 text-center text-3xl font-extrabold text-gray-900">
                 Create your account
               </h2>