Add success message to contact form

[akshay0611]

What was done:

• A success message was added to the contact form, which will appear when the form is successfully submitted.

Why it's necessary:

• The success message improves the user experience by giving clear feedback that the form has been successfully submitted.

Testing:

• Verify that the success message is shown after a successful form submission.
• Confirm that the message disappears after 3 seconds.

It closes Issue No #165

Screenshot after the change