Docs: Create styled link to DataStax Langflow in the sidebar (#7143)

add new html sidebar item with custom styles and new font

Co-authored-by: Mendon Kissling <59585235+mendonk@users.noreply.github.com>

docs/sidebars.js

@@ -213,5 +213,18 @@ module.exports = {
         },
       ],
     },
+    {
+      type: "html",
+      className: "sidebar-ad",
+      value: `
+        <a href="https://astra.datastax.com/signup?type=langflow" target="_blank" class="menu__link">
+          <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-cloud"><path d="M17.5 19H9a7 7 0 1 1 6.71-9h1.79a4.5 4.5 0 1 1 0 9Z"/></svg>
+          <div class="sidebar-ad-text-container">
+            <span class="sidebar-ad-text">Use Langflow in the cloud</span>
+            <span class="sidebar-ad-text sidebar-ad-text-gradient">Sign up for DataStax Langflow</span>
+          </div>
+        </a>
+      `,
+    },
   ],
 };