Add close-panel technical pattern to overview page.

Author: thet

index.html

@@ -313,6 +313,12 @@ <h4>Fancy stuff</h4>
                     title="Fullscreen"
                     >Fullscreen<sup>β</sup></a
                 >
+                <a
+                    class="navigation close-panel"
+                    href="/src/pat/close-panel/index.html"
+                    title="Close panel"
+                    >Close panels<sup>unknown</sup></a
+                >
             </div>
 
             <div class="fancy-examples">