Update 404 layout to better support analytics (kedacore#677)

layouts/404.html

@@ -1,10 +1,14 @@
-{{ define "main"}}
+{{ define "title" -}}
+404 Page not found | {{ site.Title -}}
+{{ end }}
+
+{{ define "main" -}}
 <section class="section">
     <div class="container">
       <div class="content is-medium is-constrained has-bottom-margin">
-        
+
         <p class="title is-size-1 is-size-2-mobile has-text-weight-bold is-spaced">
-            Woops! Dead link...
+            Woops! Page not found.
           </p>
 
         That's not very convenient, sorry about that!
@@ -16,8 +20,8 @@
             <li><a href="{{ .Site.BaseURL }}/docs/latest/deploy">How to deploy KEDA</a></li>
             <li><a href="{{ .Site.BaseURL }}/docs/latest/operate">How to operate KEDA</a></li>
         </ul>
-        
-        
+
+
         <article class="message is-info">
             <div class="message-header">
               <p class="is-size-5 is-size-6-mobile">
@@ -31,4 +35,4 @@
       </div>
     </div>
   </section>
-{{ end }}
+{{ end }}