Update copyright year in footer

Author: jumboduck

docs.kosli.com/layouts/partials/docs/footer.html

@@ -5,7 +5,7 @@
     <img class="footer-logo" src="/images/kosli-logo.svg" alt="Kosli Logo">
   </div>
   <div>
-    © 2025 Kosli Inc.
+    © 2026 Kosli Inc.
   </div>
   <div>
     <a href="https://www.kosli.com" target="_blank">kosli.com</a>