change "Tube Archivist IP" to "Tube Archivist URL"

extension/index.html

@@ -18,7 +18,7 @@
         </div>
         <hr>
         <form class="login-form">
-            <label for="url">Tube Archivist IP:</label>
+            <label for="url">Tube Archivist URL:</label>
             <input type="text" id="url" name="url">
             <label for="port">Tube Archivist Port:</label>
             <input type="text" id="port" name="port">