update copy

index.html

···
         const handle = document.getElementById("handle").value.trim();
 
         if (!handle) {
-          showError("Please enter your { }");
+          showError("Please enter your handle");
           return;
         }
 
···
           <div class="card">
             <form class="login-form" onsubmit="handleLogin(event)">
               <div class="form-group">
-                <label for="handle">Handle</label>
+                <label for="handle">AT Protocol Handle</label>
                 <qs-actor-autocomplete
                   id="handle"
                   name="handle"