CCM-9916: preload fonts with cors

Author: harrim91

docs/_layouts/default.html

@@ -9,6 +9,10 @@
   <title>
     NHS Notify - {{ page.title | default: site.title }}
   </title>
+  <link rel='preload' as='font' href='https://assets.nhs.uk/fonts/FrutigerLTW01-55Roman.woff2' type='font/woff2'
+    crossorigin="anonymous" />
+  <link rel='preload' as='font' href='https://assets.nhs.uk/fonts/FrutigerLTW01-65Bold.woff2' type='font/woff2'
+    crossorigin="anonymous" />
   <link href="{{site.baseurl}}/assets/css/main.css" rel="stylesheet">
   <script src="{{site.baseurl}}/assets/js/nhsuk.min.js" defer=""></script>