feat(website/resources): add note about icon packs

apps/website/src/pages/Resources/Resources.tsx

@@ -27,6 +27,10 @@ export default function Resources() {
         <Section className="icon-packs fill">
             <h2>{t("resources.icon_packs")}</h2>
 
+            <div>
+                <p>Note: This feature is still in preview and is available only in the <a href="https://docs.triliumnotes.org/user-guide/advanced-usage/nightly-release" target="_blank" rel="noopener noreferrer">nightly release</a>.</p>
+            </div>
+
             <p>
                 <Trans
                     i18nKey="resources.icon_packs_intro"