Add mdbook-toc to travis, book.toml and documentation

Author: igaray

.travis.yml

@@ -13,6 +13,7 @@ install:
 - source ~/.cargo/env || true
 - cargo install mdbook --version '^0.4.5'
 - cargo install mdbook-linkcheck --version '^0.7.2'
+- cargo install mdbook-toc --version '^0.6.1'
 script:
 - git checkout -b ci
 - git rebase origin/master

README.md

@@ -40,7 +40,7 @@ rustdocs][rustdocs].
 To build a local static HTML site, install [`mdbook`](https://github.com/rust-lang/mdBook) with:
 
 ```
-> cargo install mdbook mdbook-linkcheck
+> cargo install mdbook mdbook-linkcheck mdbook-toc
 ```
 
 and execute the following command in the root of the repository:
@@ -56,6 +56,11 @@ The build files are found in the `book` directory.
 We use `mdbook-linkcheck` to validate URLs included in our documentation.
 `linkcheck` will be run automatically when you build with the instructions in the section above.
 
+### Table of Contents
+
+We use `mdbook-toc` to auto-generate TOCs for long sections. You can invoke the preprocessor by
+including the `<!-- toc -->` marker at the place where you want the TOC.
+
 ### Pre-commit script
 
 We also test that line lengths are less than 100 columns. To test this locally,

book.toml

@@ -6,6 +6,10 @@ description = "A guide to developing rustc"
 [build]
 create-missing = false
 
+[preprocessor.toc]
+command = "mdbook-toc"
+renderer = ["html"]
+
 [output.html]
 git-repository-url = "https://github.com/rust-lang/rustc-dev-guide"