feat: return 404 status code when 404.html - #74

Changed pages include:

• index.html - view
• 404.html - view
• blog/index.html - view
• case-studies/index.html - view
• cloud/index.html - view
• contact/index.html - view
• now/index.html - view
• policies/index.html - view
• power-digital-case-study/index.html - view
• referral-bonus/index.html - view

There are more changes not included in the list