diff --git a/layouts/partials/sidebar/left.html b/layouts/partials/sidebar/left.html
index 177a4e8..9d4dd3e 100644
--- a/layouts/partials/sidebar/left.html
+++ b/layouts/partials/sidebar/left.html
@@ -42,7 +42,7 @@
             <a href='{{ .URL | relLangURL }}' {{ if eq .Params.newTab true }}target="_blank"{{ end }}>
                 {{ $icon := default .Pre .Params.Icon }}
                 {{ if .Pre }}
-                    {{ warnf "Menu item [%s] is using [pre] field to set icon, please use [params.icon] instead" .URL }}
+                    {{ warnf "Menu item [%s] is using [pre] field to set icon, please use [params.icon] instead.\nMore information: https://docs.stack.jimmycai.com/configuration/custom-menu.html" .URL }}
                 {{ end }}
                 {{ with $icon }}
                     {{ partial "helper/icon" . }}