Add dev hack day from btcprague

index.html

@@ -74,6 +74,7 @@ <h2>Grants</h2>
             <h2>Events</h2>
             <ul>
               <li><a href="https://btcpp.dev/">Bitcoin++</a></li>
+              <li><a href="https://btcprague.com/dev-hack-day/">BtcPrague Dev/Hack/Day</a></li>
             </ul>
           </section>
           <section id="other" class="ressourcebox">