Add title to open graph and allow page description

Author: murrant

_includes/head.html

@@ -10,13 +10,13 @@
     <meta name="msapplication-config" content="/browserconfig.xml">
     <meta name="theme-color" content="#ffffff">
     <meta name="viewport" content="width=device-width, initial-scale=1">
-    <meta name="description" content="{{ site.description }}">
+    <meta name="description" content="{% if page.description %}{{ page.description }}{% else %}{{ site.description }}{% endif %}">
     <link rel="canonical" href="{{ page.url | replace:'index.html','' | prepend: site.url }}">
 
     <!-- Open Graph -->
     <meta property="og:type" content="website">
-    <meta property="og:title" content="LibreNMS">
-    <meta property="og:description" content="{{ site.description }}">
+    <meta property="og:title" content="{% if page.title %}{{ page.title }}{% else %}{{ site.title }}{% endif %}">
+    <meta property="og:description" content="{% if page.description %}{{ page.description }}{% else %}{{ site.description }}{% endif %}">
     <meta property="og:url" content="{{ site.url }}">
     <meta property="og:site_name" content="LibreNMS">
     <meta property="og:locale" content="en_US">