user guide: Add instructions for running mdbook in CI

This adds instructions for building and testing books in CI on every PR and
push, as well as instructions for how to automatically deploy to gh-pages on
successful CI runs on `master`.

Fixes #714

book-example/src/SUMMARY.md

@@ -17,6 +17,7 @@
         - [Editor](format/theme/editor.md)
     - [MathJax Support](format/mathjax.md)
     - [mdBook specific features](format/mdbook.md)
+- [Continuous Integration](continuous-integration.md)
 - [For Developers](for_developers/README.md)
     - [Preprocessors](for_developers/preprocessors.md)
     - [Alternate Backends](for_developers/backends.md)

book-example/src/continuous-integration.md

@@ -0,0 +1,55 @@
+# Running `mdbook` in Continuous Integration
+
+While the following examples use Travis CI, their principles should
+straightforwardly transfer to other continuous integration providers as well.
+
+## Ensuring Your Book Builds and Tests Pass
+
+Here is a sample Travis CI `.travis.yml` configuration that ensures `mdbook
+build` and `mdbook test` run successfully. The key to fast CI turnaround times
+is caching `mdbook` installs, so that you aren't compiling `mdbook` on every CI
+run.
+
+```yaml
+language: rust
+sudo: false
+
+cache:
+  - cargo
+
+rust:
+  - stable
+
+before_script:
+  - (test -x $HOME/.cargo/bin/cargo-install-update || cargo install cargo-update)
+  - (test -x $HOME/.cargo/bin/mdbook || cargo install --vers "^0.1" mdbook)
+  - cargo install-update -a
+
+script:
+  - cd path/to/mybook && mdbook build && mdbook test
+```
+
+## Deploying Your Book to GitHub Pages
+
+Following these instructions will result in your book being published to GitHub
+pages after a successful CI run on your repository's `master` branch.
+
+First, create a new GitHub oauth token with the "public_repo" permissions (or
+"repo" for private repositories). Go to your repository's Travis CI settings
+page and add an environment variable named `GITHUB_TOKEN` that is marked secure
+and *not* shown in the logs.
+
+Then, add this snippet to your `.travis.yml`:
+
+```yaml
+deploy:
+  provider: pages
+  skip-cleanup: true
+  github-token: $GITHUB_TOKEN
+  local-dir: path/to/mybook/book
+  keep-history: false
+  on:
+    branch: master
+```
+
+That's it!