Add link to beta site to navbar

Change-Id: I201f2e29d3bd97847a9e6027b42656c2fd443603
diff --git a/navbar.md b/navbar.md
index 493dcfc..c922cef 100644
--- a/navbar.md
+++ b/navbar.md
@@ -8,6 +8,7 @@
 * [Source](https://gerrit.googlesource.com/gerrit/)
 * [Reviews](https://gerrit-review.googlesource.com/#/q/status:open+project:gerrit)
 * [Builds](https://gerrit-ci.gerritforge.com)
+* **[Preview our new site design!](https://gerritcodereview-test.gsrc.io)**
 
 [home]: /index.md
 [logo]: /images/diffy45.png