Add comments for future me

Author: MarkvanMents

layouts/partials/version-banner.html

@@ -3,6 +3,7 @@
     <!-- Check if the page has a banner: "string" set if yes, display a banner. -->
     <!-- safeHTML means you can include HTML. If you need to escape double quotes, use \" -->
     <!-- For example: banner: "Go <a href=\"/refguide9/moving-from-8-to-9/\">here</a>" -->
+    <!-- Extra check for empty banner added to allow empty banners in front matter to get around bug in Hugo 0.123.0 (https://github.com/gohugoio/hugo/issues/12465) which is not fixed until 0.143.0 (https://github.com/gohugoio/hugo/releases/tag/v0.143.0) -->
     {{ with .Params.banner }}
        {{ if ne . "" }}
             <div class="pageinfo pageinfo-warning">