Add ownership recap (#79)

* Add ownership recap

* Fix mdbook test issue

* Several small interventions

Updates based on question feedback (#64)

* Updates based on question feedback

* Fix several typos, grammar issues, semantic issues

Final fixups before initial release

Move all match questions to end of section

Add first major batch of interventions

Update MCQs to latest format

Merge branch 'ownership-incompleteness'

Merge branch 'borrow-promotion'

Update and clarify some text affected by the rand update

code is 1024 now, not 512