Add reference teaser above examples

Author: pepc84

index.html

@@ -126,6 +126,7 @@ <h1>C++ Mode for<br>Processing</h1>
 </div>
 
 <div class="examples-section">
+  <p style="font-size:0.95rem;color:#888;margin-bottom:0.5rem;">Explore the <a href="reference.html" style="color:#111;border-bottom:1px solid #ddd;">C++ Mode reference</a> for the full API.</p>
   <h2>Examples</h2>
   <div class="examples-grid">
     <div class="example-card">