site: add kapa widget branding text

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

layouts/partials/head.html

@@ -70,6 +70,7 @@
     script.setAttribute('data-modal-disclaimer', 'This is a custom LLM for answering questions about Docker. Answers are based on the contents of the documentation. This feature is experimental - rate the answers to let us know what you think!');
     script.setAttribute('data-modal-disclaimer-bg-color', '#e5f2fc');
     script.setAttribute('data-modal-disclaimer-text-color', '#086dd7');
+    script.setAttribute('data-kapa-branding-text', 'powered by [kapa.ai](https://www.kapa.ai) and Docker');
     script.async = true;
     document.body.appendChild(script);
   });