Add markup renderers

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

layouts/_default/_markup/render-link.html

@@ -0,0 +1,9 @@
+<a
+  href="{{- .Destination | safeURL -}}"
+  {{ with .Title }}title="{{- . -}}"{{ end }}
+  {{ if strings.HasPrefix .Destination "http" }}
+    target="_blank" rel="noopener"
+  {{ end }}
+>
+  {{ .Text | safeHTML }}
+</a>