[Docs Rewrite] Meta-Issue: General Content Improvements

[markerikson]

This is a tracking issue for all work related to improving new and existing content as part of the rewrite, beyond the actual writing.

Tasks

• Add CodeSandbox embeds to pages besides Examples
• Add diagrams
• Add references links to pages (Add "Further Information" resource links to all doc pages #2589)

[markerikson]

I added a couple of "sync/async data flow" diagrams to the new tutorials, but we could use some more diagrams.

There's a ton of them over in #653 . I saw a good one in a twitter thread at https://twitter.com/poisonivysart/status/1295809260748767233 :

apparently that's from Steven Grider's course on Udemy:

https://twitter.com/poisonivysart/status/1295848353369075716

similarly, from https://twitter.com/dev_caue/status/1310955649656815617 :

Beyond the diagrams, we may want to try adding some addition bits of info to the pages, per https://www.stephaniemorillo.co/post/7-pieces-of-information-to-include-in-technical-blog-posts .