fix: updated not found page

[Iam-Karan-Suresh]

What has changed?

Enhanced the 404 error page to provide a better user experience and fix template rendering issues. The changes include:

• Fixed broken template literals in the 404 page title
• Improved page layout and content structure
• Added clear navigation options for users
• Enhanced visual styling using Docusaurus utility classes

This PR Resolves #[issue_number] - Fix 404 page structure and template rendering

Type of change

• [x] Bug fix (non-breaking change which fixes an issue).
• [ ] New feature (non-breaking change which adds functionality).
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected).
• [ ] Documentation update (if none of the other choices apply).

How Has This Been Tested?

1. Run development server:

npm  start