Auto merge of #4923 - wking:console-markup, r=alexcrichton

doc: Replace 'shell' language labels (generally with 'console')

#GitHub [uses Linguist][1] for syntax highlighting.  Linguist's [`shell` language][2] is for the *language* (e.g. the contents of a `.sh` file).  The proper language for a shell session is [`ShellSession`][3], although in this commit I've used the [alias `console`][4].

The Cargo book [uses mdBook][4.5], mdBook [uses Highlight.js][5], and Highlight.js [also supports `console` as an alias for shell sessions][6].

A handful of places where we had been using `shell` were just command output, not shell sessions (e.g. they lacked a prompt and command).  In this commit, I've left those without a language label.

[1]: https://help.github.com/articles/creating-and-highlighting-code-blocks/#syntax-highlighting
[2]: https://github.com/github/linguist/blob/v5.3.3/lib/linguist/languages.yml#L4208
[3]: https://github.com/github/linguist/blob/v5.3.3/lib/linguist/languages.yml#L4249
[4]: https://github.com/github/linguist/blob/v5.3.3/lib/linguist/languages.yml#L4255
[4.5]: https://github.com/rust-lang/cargo/tree/f60ece98c10aa3716d037524da4ee989e212fe19/src/doc#requirements
[5]: https://rust-lang-nursery.github.io/mdBook/format/theme/syntax-highlighting.html#syntax-highlighting
[6]: https://github.com/isagalaev/highlight.js/blob/9.12.0/src/languages/shell.js#L10

Author: bors

src/doc/README.md

@@ -7,31 +7,31 @@ Building the book requires [mdBook]. To get it:
 
 [mdBook]: https://github.com/azerupi/mdBook
 
-```shell
+```console
 $ cargo install mdbook
 ```
 
 ### Building
 
 To build the book:
 
-```shell
+```console
 $ mdbook build
 ```
 
 The output will be in the `book` subdirectory. To check it out, open it in
 your web browser.
 
 _Firefox:_
-```shell
+```console
 $ firefox book/index.html                       # Linux
 $ open -a "Firefox" book/index.html             # OS X
 $ Start-Process "firefox.exe" .\book\index.html # Windows (PowerShell)
 $ start firefox.exe .\book\index.html           # Windows (Cmd)
 ```
 
 _Chrome:_
-```shell
+```console
 $ google-chrome book/index.html                 # Linux
 $ open -a "Google Chrome" book/index.html       # OS X
 $ Start-Process "chrome.exe" .\book\index.html  # Windows (PowerShell)

src/doc/src/getting-started/first-steps.md

@@ -2,7 +2,7 @@
 
 To start a new project with Cargo, use `cargo new`:
 
-```shell
+```console
 $ cargo new hello_world --bin
 ```
 
@@ -11,7 +11,7 @@ were making a library, we’d leave it off.
 
 Let’s check out what Cargo has generated for us:
 
-```shell
+```console
 $ cd hello_world
 $ tree .
 .
@@ -44,21 +44,21 @@ fn main() {
 
 Cargo generated a “hello world” for us. Let’s compile it:
 
-```shell
+```console
 $ cargo build
    Compiling hello_world v0.1.0 (file:///path/to/project/hello_world)
 ```
 
 And then run it:
 
-```shell
+```console
 $ ./target/debug/hello_world
 Hello, world!
 ```
 
 We can also use `cargo run` to compile and then run it, all in one step:
 
-```shell
+```console
 $ cargo run
      Fresh hello_world v0.1.0 (file:///path/to/project/hello_world)
    Running `target/hello_world`

src/doc/src/getting-started/installation.md

@@ -5,7 +5,7 @@
 The easiest way to get Cargo is to get the current stable release of [Rust] by
 using the `rustup` script:
 
-```shell
+```console
 $ curl -sSf https://static.rust-lang.org/rustup.sh | sh
 ```
 

src/doc/src/guide/cargo-toml-vs-cargo-lock.md

@@ -92,7 +92,7 @@ they’ll use the exact same SHA, even though we didn’t specify it in our
 When we’re ready to opt in to a new version of the library, Cargo can
 re-calculate the dependencies and update things for us:
 
-```shell
+```console
 $ cargo update           # updates all dependencies
 $ cargo update -p rand   # updates just “rand”
 ```

src/doc/src/guide/creating-a-new-project.md

@@ -2,7 +2,7 @@
 
 To start a new project with Cargo, use `cargo new`:
 
-```shell
+```console
 $ cargo new hello_world --bin
 ```
 
@@ -12,7 +12,7 @@ repository by default. If you don't want it to do that, pass `--vcs none`.
 
 Let’s check out what Cargo has generated for us:
 
-```shell
+```console
 $ cd hello_world
 $ tree .
 .
@@ -47,14 +47,14 @@ fn main() {
 
 Cargo generated a “hello world” for us. Let’s compile it:
 
-```shell
+```console
 $ cargo build
    Compiling hello_world v0.1.0 (file:///path/to/project/hello_world)
 ```
 
 And then run it:
 
-```shell
+```console
 $ ./target/debug/hello_world
 Hello, world!
 ```
@@ -63,7 +63,7 @@ We can also use `cargo run` to compile and then run it, all in one step (You
 won't see the `Compiling` line if you have not made any changes since you last
 compiled):
 
-```shell
+```console
 $ cargo run
    Compiling hello_world v0.1.0 (file:///path/to/project/hello_world)
      Running `target/debug/hello_world`
@@ -76,7 +76,7 @@ dependencies. Since we don’t have any yet, it’s not very interesting.
 Once you’re ready for release, you can use `cargo build --release` to compile
 your files with optimizations turned on:
 
-```shell
+```console
 $ cargo build --release
    Compiling hello_world v0.1.0 (file:///path/to/project/hello_world)
 ```

src/doc/src/guide/dependencies.md

@@ -44,7 +44,7 @@ regex = "0.1.41"
 Re-run `cargo build`, and Cargo will fetch the new dependencies and all of
 their dependencies, compile them all, and update the `Cargo.lock`:
 
-```shell
+```console
 $ cargo build
       Updating registry `https://github.com/rust-lang/crates.io-index`
    Downloading memchr v0.1.5
@@ -83,7 +83,7 @@ fn main() {
 
 Running it will show:
 
-```shell
+```console
 $ cargo run
    Running `target/hello_world`
 Did our date match? true

src/doc/src/guide/project-layout.md

@@ -3,7 +3,7 @@
 Cargo uses conventions for file placement to make it easy to dive into a new
 Cargo project:
 
-```shell
+```
 .
 ├── Cargo.lock
 ├── Cargo.toml

src/doc/src/guide/tests.md

@@ -9,7 +9,7 @@ the files in `tests`.
 Here's an example of running `cargo test` in our project, which currently has
 no tests:
 
-```shell
+```console
 $ cargo test
    Compiling rand v0.1.0 (https://github.com/rust-lang-nursery/rand.git#9f35b8e)
    Compiling hello_world v0.1.0 (file:///path/to/project/hello_world)
@@ -25,7 +25,7 @@ tests.
 
 You can also run a specific test by passing a filter:
 
-```shell
+```console
 $ cargo test foo
 ```
 

src/doc/src/guide/working-on-an-existing-project.md

@@ -6,14 +6,14 @@ to get going.
 First, get the project from somewhere. In this example, we’ll use `rand`
 cloned from its repository on GitHub:
 
-```shell
+```console
 $ git clone https://github.com/rust-lang-nursery/rand.git
 $ cd rand
 ```
 
 To build, use `cargo build`:
 
-```shell
+```console
 $ cargo build
    Compiling rand v0.1.0 (file:///path/to/project/rand)
 ```

src/doc/src/reference/build-scripts.md

@@ -56,7 +56,7 @@ if you want to ensure that output is always displayed on your terminal.
 Any line that starts with `cargo:` is interpreted directly by Cargo.
 This line must be of the form `cargo:key=value`, like the examples below:
 
-```shell
+```
 # specially recognized by Cargo
 cargo:rustc-link-lib=static=foo
 cargo:rustc-link-search=native=/path/to/foo
@@ -219,7 +219,7 @@ library call as part of the build script.
 
 First, let’s take a look at the directory structure of this package:
 
-```shell
+```
 .
 ├── Cargo.toml
 ├── build.rs
@@ -305,7 +305,7 @@ a Rust library which calls into C to print “Hello, World!”.
 
 Like above, let’s first take a look at the project layout:
 
-```shell
+```
 .
 ├── Cargo.toml
 ├── build.rs