Add showcase open call to header

Author: Qianqianye

src/templates/partials/header.hbs

@@ -15,5 +15,6 @@ title: header
 
   {{!-- <a id="promo-link" href="https://donorbox.org/supportp52020" target="_blank"><div id="promo">This season, we need your help! Click here to #SupportP5!</div></a> --}}
   {{!-- <a id="promo-link" href="https://donorbox.org/processingfoundation2021" target="_blank"><div id="promo">This season, we need your help! Click here to #SupportP5!</div></a> --}}
+  <a id="promo-link" href="https://bit.ly/p5showcase2022" target="_blank"><div id="promo">Submit to the p5.js 2022 Showcase! Due August 14!</div></a>
 
 </nav>