Added 404 page

layouts/404.html

@@ -0,0 +1,27 @@
+{{ partial "header" . }}
+{{ $currentURL := .URL }}
+
+<div class="actix-pageheader">
+  <div class="container">
+    <h1 class="display-4">404: Page Not Found</h1>
+    <p class="lead">What you were looking for was not here</p>
+  </div>
+</div>
+
+<div class="container actix-community">
+  <div class="row">
+    <div class="col-md-6 offset-md-3">
+      <div class="actix-content">
+        <h1>Not Found</h1>
+        <p>We could not find the page you were looking for.  This website was
+        recently restructured so maybe a link went dead.
+        <ul>
+          <li><a href="/">Home page</a>
+          <li><a href="/docs/">Documentation</a>
+        </ul>
+      </div>
+    </div>
+  </div>
+</div>
+
+{{ partial "footer" . }}