Add Success Message to Subscribe Form

[akshay0611]

Problem: The current subscription form in the footer does not provide feedback to users after they submit their email address. This can lead to confusion about whether their submission was successful.

Proposed Solution:

• Add a success message that appears after the user submits the form.
• Use JavaScript to dynamically display the success message upon form submission.

Expected Outcome: A more user-friendly subscription form that confirms successful submissions, improving the overall user experience.