Updated .env.example to enable correctly DEBUG mode in Flask

Author: Tozzigh

.env.example

@@ -7,7 +7,8 @@ DATABASE_URL=postgres://gitpod:postgres@localhost:5432/example
 FLASK_APP_KEY="any key works"
 FLASK_APP=src/app.py
 FLASK_ENV=development
+DEBUG=TRUE
 
 # Front-End Variables
 BASENAME=/
-#BACKEND_URL=
+#BACKEND_URL=