Update _config.yml

Author: PureGero

_config.yml

@@ -5,4 +5,10 @@ theme: just-the-docs
 url: https://multipaper.github.io/
 
 aux_links:
-  Template Repository: https://github.com/just-the-docs/just-the-docs-template
+  GitHub: https://github.com/MultiPaper/MultiPaper
+  Discord: https://discord.gg/dN3WCZkSRV
+
+callouts:
+  warning:
+    title: Warning
+    color: red