Update nav.pug

Author: fearnot221

includes/nav.pug

@@ -17,7 +17,7 @@ section#title.hero.cover-image.is-fullheight.is-bold
       h2.subtitle.is-size-5.has-text-weight-bold
         | Students' Community of Information in Southern Taiwan
       br
-      a.button.is-link.is-light.pulsing(href="https://dc.scist.org" target="_blank" rel="noopener noreferrer" style="margin-bottom: 10px;")
+      a.button.is-link.is-light.pulsing(href="https://discord.gg/Ff6xZXNQq9" target="_blank" rel="noopener noreferrer" style="margin-bottom: 10px;")
         span.icon
           i.fab.fa-discord
         span 加入 Discord 伺服器