Update home page with banner

packages/lit-dev-content/site/home/1-splash.html

@@ -1,12 +1,8 @@
 <section id="new-banner">
   <p>
-    <span class="emoji">💡</span>
-    Lit.dev now supports dark mode. Try it out by toggling it in the top menu.
-    <a
-        href="https://github.com/lit/lit.dev/issues/new?body=%3Cdescription+of+issue%3E+renders+incorrectly+in+dark+mode.%0A%0AURL%3A+%3Curl+to+page%3E%0A%0Abrowser+info%3A+%3Cbrowser+name+and+version%3E%0A%0AOS%3A+%3Cos+platform+and+version%3E%0A%0AScreenshot%3A+%3Cpaste+a+screenshot+here%3E&title=%5BDark+Mode%5D%3A+%3Cissue+title%3E"
-        target="_blank">
-      Feedback welcome!
-    </a>
+    <span class="emoji">🚦</span>
+    Our newest Lit Labs package <code>@lit-labs/signals</code> is now available!
+    Check out the announcement <a href="https://lit.dev/blog/2024-10-02-signals/">here</a>.
   </p>
 </section>
 <section id="intro">