added a recover function and updated create key function

[Rohit-Kumar-Jha-IIT-Roorkee]

closes issue #29

type of change: 1) New feature
2)Documentation update

Description of change:

backup key with security question:
after creating a new key, the program will ask to set a security question (like "What is your pet's name?") and provide an answer. It then saves a backup key, which is encrypted using your answer, in a separate file. This ensures that even if you lose the main key, you can still recover it.

key recovery option:
If you lose the main key, the program gives you an option to recover the key by answering the security question correctly. It will use your answer to decrypt the backup key and restore access to your passwords.

also i added the elif choice in main.py to show an option to recover password

implementation details:

files Updated:
create_key() in manager.py
added recover_key() in manager.py
modified main() in main.py to include a recovery option.

demo: