added og description

src/views/header.tpl

@@ -3,6 +3,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <meta name="author" content="chimchooree">
     <meta name="description" content="{{preview}}">
+    <meta property="og:description" content="{{preview}}" />
     <link rel="stylesheet" type="text/css" href="/static/css/all.css">
     <link rel="stylesheet" type="text/css" href="/static/css/nav.css">
     <link rel="stylesheet" type="text/css" href="/static/css/sidebar.css">