Added favicon, fixed alt text

docs/_layouts/default.html

@@ -4,6 +4,9 @@
     <meta charset='utf-8'>
     <meta http-equiv="X-UA-Compatible" content="chrome=1">
     <meta name="viewport" content="width=device-width, initial-scale=1">
+    <link rel="icon" type="image/png" sizes="16x16" href="{{ '/assets/images/favicon-16x16.png' | relative_url }}">
+    <link rel="icon" type="image/png" sizes="32x32" href="{{ '/assets/images/favicon-32x32.png' | relative_url }}">
+    <link rel="icon" type="image/png" sizes="32x32" href="{{ '/assets/images/favicon-32x32.png' | relative_url }}">
     <link rel="stylesheet" href="{{ '/assets/css/style.css?v=' | append: site.github.build_revision | relative_url }}">
     {% seo %}
   </head>
@@ -14,7 +17,7 @@
         <div class="sidebar" id="sidebar">
         <hr class="mobile-divide" />
             <div class="container">
-          <a href="{{ site.baseurl }}{% link index.md %}"><img src="{{ '/assets/images/enigma-logo.png' | relative_url }}" class="logo" /></a>
+          <a href="{{ site.baseurl }}{% link index.md %}"><img src="{{ '/assets/images/enigma-logo.png' | relative_url }}" class="logo" alt="Enigma logo" /></a>
             </div>
             {% capture nav_include %}{% include nav.md %}{% endcapture %}
             {{ nav_include | markdownify }}