doc/dev/mdbook.md

## Settings

We are using the following settings while editing the markdown docs.

```json
{
    "files.insertFinalNewline": true,
    "files.trimTrailingWhitespace": true,
    "[markdown]": {
        "rewrap.wrappingColumn": 70
    }
}
```

## Build

This manual is generated by
[mdBook](https://github.com/rust-lang/mdBook). We are currently using
a [fork](https://github.com/leanprover/mdBook) of it for the following
additional features:

* Add support for hiding lines in other languages
  [#1339](https://github.com/rust-lang/mdBook/pull/1339)
* Replace calling `rustdoc --test` from `mdbook test` with `./test`

To build this manual, first install the fork via
```bash
cargo install --git https://github.com/leanprover/mdBook mdbook
```
Then use e.g. [`mdbook watch`](https://rust-lang.github.io/mdBook/cli/watch.html) in the `doc/` folder:

```bash
cd doc
mdbook watch --open  # opens the output in `out/` in your default browser
```

Run `mdbook test` to test all `lean` code blocks.

Using the [Nix setup](make/nix.md), you can instead open a shell with
the mdBook fork downloaded from our binary cache:
```bash
nix develop .#doc
```