Docs homepage feedback

[mhwelander]

• Render title, description, keywords from siteMetaData in config.js. Currently site has no title or meta description.
• Headings jump straight from h1 to h3 - promote current h3s to h2s, h4s to h3, and so on

[Jolg42]

• 404 link on page text = FAQ - value = https://www.prisma.io/about/faq
• canonical missing