Update mdBook

[camelid]

Currently on version 0.3.7 and the newest version is 0.4.3, so there are breaking changes.

Relevant file:

cargo/.github/workflows/main.yml

Lines 97 to 100 in 13b73cd

	- run: |
	mkdir mdbook
	curl -Lf https://github.com/rust-lang/mdBook/releases/download/v0.3.7/mdbook-v0.3.7-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=./mdbook
	echo ::add-path::`pwd`/mdbook

[camelid]

Also, why are we not using cargo install?

[rustbot]

Error: The feature relabel is not enabled in this repository.
To enable it add its section in the triagebot.toml in the root of the repository.

Please let @rust-lang/release know if you're having trouble with this bot.

[ehuss]

The version shouldn't matter, it is only used for linkchecking. As for installation, downloading the binary is significantly faster.

[camelid]

The version shouldn't matter, it is only used for linkchecking.

Ah okay, I didn't notice that.

As for installation, downloading the binary is significantly faster.

Oops, I forgot that cargo install builds from source :)

[camelid]

Where is the book actually built for the website then?

[ehuss]

All the books are built in the rust-lang/rust repo as part of the normal build. The code is in bootstrap, and can be built with commands like x.py doc src/tools/cargo/src/doc (though it is extremely rare anyone needs to do that manually).

[camelid]

Okay, thanks! I'll close this issue then and do it upstream.