feat: rename examples to cookbook, add banner image

Author: goosewin

fern/examples.mdx renamed to fern/cookbook.mdx

@@ -1,9 +1,13 @@
 ---
-title: Examples Library
-subtitle: Explore complete examples with step-by-step instructions to build with Vapi
-slug: examples
+title: Vapi Cookbook
+subtitle: Explore real-world, cloneable examples to build voice agents with Vapi. Now including new Workflow-based recipes!
+slug: cookbook
 ---
 
+<Frame>
+  <img src="./static/images/cookbook-banner.png" alt="Vapi Cookbook" />
+</Frame>
+
 <CardGroup cols={2}>
   <Card title="Docs Agent" icon="book-open" href="/assistants/examples/docs-agent">
     <div className='absolute top-4 right-4'>