Move onBrokenMarkdownLinks to hooks section - #20

Changed pages include:

• index.html - view
• 404.html - view
• about-us.html - view
• apis.html - view
• contact-us.html - view
• contribute.html - view
• engine.html - view
• faqs.html - view
• governance.html - view
• intro.html - view

There are more changes not included in the list