Turn 'core functionality' into a cheatsheet

[penelopeysm]

core functionality includes some not very core functionality. also the demonstrations are a bit too complex imo

I think it makes sense to turn it into a cheatsheet, 'learn Turing in 5 minutes' kind of thing (see https://learnxinyminutes.com/), and each section in it should link to more thorough docs on the page

that way it becomes something where

1. new users can quickly gauge what Turing is capable of doing

2. existing users who just need a refresher on syntax can see it immediately without wading through loads of text

3. the text is grouped onto individual pages nicely

[shravanngoswamii]

I’d love to see this happen. Let me know how I can help!

[penelopeysm]

A first step might be to just enumerate the topics that we want to cover. e.g.

• model definition
• conditioning and fixing
• MCMC sampling
• optimisation
• VI
• ...

then check which of those have docs pages, and write those that don't exist yet.