Rollup merge of rust-lang#47753 - steveklabnik:update-book, r=alexcri…

…chton

Update book

This PR does two things:

1. update the book to include rust-lang/book#1088
2. update to mdbook 0.1

Both of these things are big changes, so I want to land them now, well before the next branch, so we can kick the tires.

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Locally, I'm seeing some weirdness around the reference and this:

![image](https://user-images.githubusercontent.com/27786/35411917-8dcbb31a-01e8-11e8-8c30-0bd280d93b9d.png)

Putting this PR up so others can try and build and see if it reproduces for them.