📝 Add FastAPI monitoring blog post to External Links (#2324)

https://github.com/tiangolo/fastapi/issues/1828#issuecomment-723541832

docs/en/data/external_links.yml

@@ -144,6 +144,10 @@ articles:
       title: HTTP server to display desktop notifications
       author_link: https://julienharbulot.com/
       author: Julien Harbulot
+    - link: https://guitton.co/posts/fastapi-monitoring/
+      title: How to monitor your FastAPI service
+      author_link: https://twitter.com/louis_guitton
+      author: Louis Guitton
   japanese:
     - link: https://qiita.com/mtitg/items/47770e9a562dd150631d
       title: FastAPI｜DB接続してCRUDするPython製APIサーバーを構築