Update README.md

Author: app-generator

README.md

@@ -89,11 +89,11 @@ $ pip3 install -r requirements.txt
 ```bash
 $ # CMD 
 $ set FLASK_APP=run.py
-$ set FLASK_ENV=True
+$ set FLASK_DEBUG=True
 $
 $ # Powershell
 $ $env:FLASK_APP = ".\run.py"
-$ $env:FLASK_ENV = "True"
+$ $env:FLASK_DEBUG = "True"
 ```
 
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