feat: add a link to pianii.com

Author: aradzie

packages/keybr-pages-browser/lib/SubMenu.tsx

@@ -26,6 +26,13 @@ export function SubMenu({ currentPath }: { readonly currentPath: string }) {
       <LocaleSwitcher currentPath={currentPath} />
       <TranslateLink />
       <RemoveAdsLink />
+      <StaticLink
+        href="https://pianii.com"
+        target="pianii"
+        title="Piano sheet reading learning"
+      >
+        pianii.com
+      </StaticLink>
     </div>
   );
 }