Update to Hugo 0.53 and remove all .Site references (#12079)

* Remove all .Site variable references

* Update Hugo version in Travis CI config and Makefile

layouts/shortcodes/blocks/kubernetes-features.html

@@ -17,7 +17,7 @@ Note that markdown can be used in the description.
 <section id="features">
     <main>
         <h3 class="center">{{ T "main_kubernetes_features" }}</h3>
-        {{ $pages := where .Site.Pages ".Params.feature" "!=" nil }}
+        {{ $pages := where site.Pages ".Params.feature" "!=" nil }}
         {{range $i, $p := $pages }}
         {{ if and (gt $i 0) (modBool $i 2) }}</div>{{ end }}
         {{ if modBool $i 2 }}
@@ -33,4 +33,4 @@ Note that markdown can be used in the description.
      
         {{ end }}
     </main>
-</section>
+</section>