add a thanks page to our doc

Created by: Johann-S

• Improve the style
• Add Netlify
• List OC sponsors/backers by Tier
• Switch to a plain list with just the images?
• Fix removed/obsolete core classes usage
• Add the amount of each person's contribution as the image title?
• Add direct buttons to OC for each Tier
• Reword page header
• Fix page description
• See if we need markdownify or chomp in any of those fields
• Move inline styles to css
• Move inline JS to a separate JS file or HTML include, preferably the first
• Add page link in the sidebar
• Have this in the homepage instead of a separate page?
• Check everything in dark mode

Live previews

• Homepage (with new supporting section)
• Sponsors dedicated page