Document `--show-type-layout` in the rustdoc book
Document `--show-type-layout` in the rustdoc book

aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust