welcome to pdf

[linhexu]

Description

This pull request introduces a welcome message on the first-time execution of the Stirling-PDF application, providing users with an explanation of what local hosting is and its benefits. The motivation behind this change is to enhance the onboarding experience for new users, ensuring they understand the context of using a locally hosted application. This feature is particularly useful for users who may not be familiar with the concept of local hosting and how it differs from cloud-based solutions.

Closes #2110

Checklist

• [✓] I have read the Contribution Guidelines
• [✓] I have performed a self-review of my own code
• [✓] I have attached images of the change if it is UI based (Not applicable in this case as the change is not UI-based)
• [✓] I have commented my code, particularly in hard-to-understand areas
• [✓] My changes generate no new warnings
• [✓] I have read the section Add New Translation Tags (Not applicable in this case as no new translation tags were added)

Additional Notes

I have added a welcome message to the home.html file, which is displayed when the application is first executed. The message explains the concept of local hosting and its advantages. I have also created a separate CSS file welcome-message.css to style the welcome message appropriately. No new warnings were generated after integrating these changes, and the code has been thoroughly commented to ensure ease of understanding.