Enh: Add infrastructure to support a new packaging page

[lwasser]

this closes #317

This adds infrastructure and content to support a packaging page in the main website. This will

• surface sections of our packaging guide via cards
• surface tutorials
• describe our community driven review content dev approach

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• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1206284857099957
  • https://app.asana.com/0/0/1206424122977898

[lwasser]

ok y'all - this is now ready for review. the preview should be ready in just a few moments. this pr

1. adds a new packaging drop down to the website including a packaging landing page with links to many pages in our guidebook
2. adds cards for each new tutorial (total of 3 now) and summary cards for guidebook sections with links
3. more links are good for seo as it will help crawlers discover all of the nested content in our guidbook that had a bad sitemap for the past 1.5 years 🙈 oops
4. should help people looking for help to find our guidebook.

it doesn't mention discourse but i suppose it could? let me know what you think! let's leave this up for review for a week with the intent on merging it next tuesday Jan 30!

[lwasser]

@kierisi thank you for all the feedback and design back and forth! i'm going to merge this now as everything has been addressed. 🚀