Update index.html adding Discord icon

Author: wyattrlindsey

index.html

@@ -63,7 +63,7 @@ <h3 class="text-center">
 	<a class="uk-button uk-button-primary uk-flex uk-flex-center"
         href="https://discord.gg/yEbyed8e"
         target="blank" rel="noopener">
-        <span class="button-icon" uk-icon="icon: discord"></span>
+        <i class="fa-brands fa-discord button-icon"></i>
         <span>Join Our Discord</span>
     </a>
 </div>