Add warning about fake Discord servers

See https://wurstforum.net/d/1568

Author: Alexander01998

_includes/header.html

@@ -1,3 +1,9 @@
+<aside class="ribbed-amber padding10 text-bold">
+	<div class="container align-center">
+		<b>PSA:</b> Wurst does NOT have a Discord server. Beware of scam Discord servers pretending to be Wurst.
+	</div>
+</aside>
+
 <header class="wi-header">
 	<nav class="wi-navbar container">
 		<div class="wi-logo">