Add support for mdbook (for documentation)

Dockerfile

@@ -12,6 +12,8 @@ ARG TOOLCHAIN=stable
 # We also set up a `rust` user by default, in whose account we'll install
 # the Rust toolchain.  This user has sudo privileges if you need to install
 # any more software.
+#
+# `mdbook` is the standard Rust tool for making searchable HTML manuals.
 RUN apt-get update && \
     apt-get install -y \
         build-essential \
@@ -30,7 +32,12 @@ RUN apt-get update && \
         gcc-4.7-multilib-arm-linux-gnueabihf \
         && \
     apt-get clean && rm -rf /var/lib/apt/lists/* && \
-    useradd rust --user-group --create-home --shell /bin/bash --groups sudo
+    useradd rust --user-group --create-home --shell /bin/bash --groups sudo && \
+    MDBOOK_VERSION=0.1.5 && \
+    curl -LO https://github.com/rust-lang-nursery/mdBook/releases/download/v$MDBOOK_VERSION/mdbook-v$MDBOOK_VERSION-x86_64-unknown-linux-musl.tar.gz && \
+    tar xf mdbook-v$MDBOOK_VERSION-x86_64-unknown-linux-musl.tar.gz && \
+    mv mdbook /usr/local/bin/ && \
+    rm -f mdbook-v$MDBOOK_VERSION-x86_64-unknown-linux-musl.tar.gz
 
 # Allow sudo without a password.
 ADD sudoers /etc/sudoers.d/nopasswd

README.md

@@ -33,11 +33,17 @@ With a bit of luck, you should be able to just copy your application binary from
 
 You can also use the following libraries with a bit of setup:
 
-- SQLite3 with
-  `diesel`. See [examples/using-diesel](./examples/using-diesel/).
+- SQLite3 with `diesel`. See [examples/using-diesel](./examples/using-diesel/).
 
 This library also sets up the environment variables needed to compile popular Rust crates using these libraries.
 
+## Extras
+
+This image also supports the following extra goodies:
+
+- Basic compilation for `armv7` using `musl-libc`. Not all libraries are supported at the moment, however.
+- [`mdbook`][mdbook] for building searchable HTML documentation from Markdown files. Build manuals to use alongside your `cargo doc` output!
+
 ## Making OpenSSL work
 
 If your application uses OpenSSL, you will also need to take a few extra steps to make sure that it can find OpenSSL's list of trusted certificates, which is stored in different locations on different Linux distributions. You can do this using [`openssl-probe`](https://crates.io/crates/openssl-probe) as follows:
@@ -152,6 +158,7 @@ Either the [Apache 2.0 license](./LICENSE-APACHE.txt), or the
 [MIT license](./LICENSE-MIT.txt).
 
 [Alpine Linux container]: https://hub.docker.com/_/alpine/
+[mdbook]: https://github.com/rust-lang-nursery/mdBook
 [musl-libc]: http://www.musl-libc.org/
 [musl-gcc]: http://www.musl-libc.org/how.html
 [rustup]: https://www.rustup.rs/