Update the date for Wagtail Space US

docs/_templates/layout.html

@@ -104,7 +104,7 @@
             <a href="https://us.wagtail.space/">
                 <div>
                     <strong>Wagtail Space US</strong>
-                    <br>June 2024 in Philadelphia, USA
+                    <br>20 &ndash; 22 June 2024 in Philadelphia, USA
                 </div>
             </a>
             <button class="close" aria-label="Hide banner" aria-expanded="true" type="button" data-clear>&#x2715;</button>