message: Fixes Preload pdfworker in the generator
  This was 'suggested' by PageSpeed Insights, see this Google post for more info:
diff: <link rel="preload" as="font" crossorigin type="font/woff2" href="https://static.dacdn.de/fonts/fira-sans/fira-sans-v8-latin-regular.woff2">
  <link rel="preload" as="font" crossorigin type="font/woff2" href="https://static.dacdn.de/fonts/fira-sans/fira-sans-v8-latin-600.woff2">
  <link rel="preload" as="font" crossorigin type="font/woff2" href="https://static.dacdn.de/fonts/league-spartan/league-spartan-600.woff2">
  + {{ if eq .Type "generator" -}}
  + <link rel="preload" as="script" href="{{ "js/pdfworker.gen.js" | absURL }}">
  + {{- end }}
  <link rel="stylesheet" href="https://static.dacdn.de/fonts/fira-sans.css">
  <link rel="stylesheet" href="https://static.dacdn.de/fonts/league-spartan.css">
  <link rel="stylesheet" href="{{ "css/style.gen.css" | absURL }}"/>
  