I'm not sure how up to date that document is - the latest version of Rust I can find that includes it was 1.12.0. Here's some more recent links:
The 'official' code style guidelines are now managed through rustfmt RFCs, and documented in their style guide.
Rust design patterns such as builders are described on the unofficial Rust Patterns repo. They don't seem to be mentioned specifically in the official docs anywhere, which is a little weird given how pervasive they are in the ecosystem.