Add p5.js libraries open call on the banner

Author: Qianqianye

src/templates/partials/header.hbs

@@ -13,7 +13,7 @@ title: header
   </ul>
   <a tabindex="1" href="#content" id="skip-to-content">Skip to main content</a>
 
-  <a id="promo-link" href="https://openprocessing.org/curation/87594" target="_blank"><div id="promo">Submit your sketch to be featured on the new p5.js website by March 31!</div></a>
+  <a id="promo-link" href="https://github.com/processing/p5.js-libraries" target="_blank"><div id="promo">Submit your p5.js libraries to be featured on the new p5.js website by April 8!</div></a>
   {{!-- <a id="promo-link" href="https://donorbox.org/to-the-power-of-10" target="_blank"><div id="promo">Support p5.js and the Processing Foundation and earn unique rewards.🎉</div></a> --}}
 
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