update readme and flask exercise

054-day/hello_flask/hello.py

@@ -10,5 +10,9 @@ def hello_world():
 def hello_bye():
     return "<p>Bye</p>"
 
+@app.route("/username/<name>/<int:age>")
+def greetings(name, age):
+    return f"<p>Hello there {name}, you are {age} years older.</p>"
+
 if __name__ == "__main__":
-    app.run()
+    app.run(debug=True)

README.md

@@ -376,7 +376,7 @@ In this section, we focus on file operations:
 
 </details>
 
-### Day 54
+### Day 55
 <details>
 <summary>HTM, URL paths and Flask debugging </summary>