Update comments about internal templates

layouts/_default/baseof.html

       {{ end }}
     {{ end }}
     
-    {{/* NOTE: These Hugo Internal Templates can be found starting at https://github.com/spf13/hugo/blob/master/tpl/tplimpl/template_embedded.go#L158 */}}
+    {{/* NOTE: These Hugo Internal Templates can be found starting at https://github.com/gohugoio/hugo/tree/master/tpl/tplimpl/embedded/templates */}}
     {{- template "_internal/opengraph.html" . -}}
     {{- template "_internal/schema.html" . -}}
     {{- template "_internal/twitter_cards.html" . -}}