fix(content): add @mozilla.com email note

app/styles/app.scss

@@ -86,4 +86,11 @@ a, h1, h2, h3, h4, h5, h6, button, .button, th, p, legend, label {
     font-size: 20px;
     font-weight: bold;
   }
-}
+}
+
+.alert-box.secondary-notification {
+  border-color: #c7c7c7;
+  background: #e7e7e7;
+  color: $primary-color;
+  text-align: center;
+}

app/templates/login.hbs

@@ -8,4 +8,8 @@
     </p>
   </div>
 </div>
+<div data-alert class="alert-box secondary secondary-notification">
+  To login to this console you must create and verify a Firefox Account on this {{server}} development server.<br/>
+  Only <strong>@mozilla.com</strong> emails are allowed to login to this console.
+</div>
 {{outlet}}