Add a way to delete completed task + "Write something" label

[Vikbobvia]

Edit to ToDo.py I added feature to delete selected completed task

selected_complete_task = completed_listbox.curselection()
if selected_complete_task:
      completed_listbox.delete(selected_complete_task)

Label at the top of to-do list for people to know where to write

entry_label = tk.Label(root, text="Write Something")
entry_label.pack()