Correction de la syntaxe de l'avertissement de sécurité dans le README

Author: yoanbernabeu

README.md

@@ -64,7 +64,7 @@ The admin interface will be available at: `http://localhost:8000/admin`
 
 ## Production Deployment
 
-:::warning
+::: warning
 Please, secure your server before deploying this application to production.
 :::