dashboard: deprecation notice for the old dashboard

R=golang-dev, dsymonds, rsc
CC=golang-dev
https://golang.org/cl/5505056

misc/dashboard/godashboard/main.html

@@ -18,6 +18,9 @@
     <h1>Go Dashboard</h1>
     
     <h2>Build Status</h2>
+
+    <p class="notice">The build status dashboard has moved to <a href="http://build.golang.org">build.golang.org</a>.</p>
+
     <table class="alternate" cellpadding="0" cellspacing="0">
       <tr>
         <th></th>

misc/dashboard/godashboard/static/style.css

@@ -116,3 +116,14 @@ div.paginate a.inactive {
 td.time {
 	font-family: monospace;
 }
+.notice {
+	padding: 10px;
+	margin: 10px;
+	border: 2px solid #FF6;
+	background: #900;
+	color: white;
+	text-align: center;
+}
+.notice a {
+	color: #FF6;
+}