Book, config: TOML syntax highlighting broken

[felixrabe]

The syntax highlighting of the long TOML section at https://doc.rust-lang.org/cargo/reference/config.html#configuration-keys looks wrong:

The section correctly starts with a ```toml fence:

cargo/src/doc/src/reference/config.md

Line 43 in ceb1389

```toml

Btw, GitHub seems to display that same section just fine:

https://github.com/rust-lang/cargo/blob/ceb1389037ff4987a9a51066a173012ee18861dc/src/doc/src/reference/config.md#configuration-keys

[ehuss]

Yea, that's bugged me for a while. The problem is that the highlighting engine (highlight.js) doesn't highlight toml properly. Either highlight.js needs to be updated to handle comments after keys, or mdbook needs to switch to a different highlighter. Fixing highlight.js doesn't look too difficult.

[tesuji]

cc rust-lang/mdBook#890

[ehuss]

This is now fixed on nightly.