Improve open graph tags

Fixes #1089.

--
MOS_MIGRATED_REVID=125562955
diff --git a/site/_includes/head.html b/site/_includes/head.html
index c2fc78d..57bad5c 100644
--- a/site/_includes/head.html
+++ b/site/_includes/head.html
@@ -34,8 +34,6 @@
     <link rel="stylesheet" type="text/css" href="/css/main.css" />
 
     <!-- metadata -->
-    <meta name="og:title" content="Bazel"/>
+    <meta name="og:title" content="{{ page.title }}"/>
     <meta name="og:image" content="/images/bazel-og-image.png"/>
-    <meta name="og:description" content="Correct, reproducible, fast builds for everyone"/>
   </head>
-