Menu: add top-level Discord link

Author: swharden

layouts/partials/menu.html

@@ -106,11 +106,17 @@
         </li>
 
         <li class="nav-item">
-            <a class=" nav-link" href="/faq">
+            <a class="nav-link" href="/faq">
                 FAQ
             </a>
         </li>
 
+        <li class="nav-item">
+            <a class="nav-link" href="/discord">
+                Discord
+            </a>
+        </li>
+
         <li class="nav-item">
             <a class="nav-link" href="https://github.com/scottplot/scottplot/">
                 GitHub