Add link to changelog in the Cargo book.
Add link to changelog in the Cargo book.

rust-lang/cargo,rustyhorde/cargo,tshepang/cargo,rustyhorde/cargo,nipunn1313/cargo,rustyhorde/cargo,rust-lang/cargo,tshepang/cargo,rustyhorde/cargo,eminence/cargo,tshepang/cargo,nipunn1313/cargo,eminence/cargo,tsurai/cargo,rust-lang/cargo,rust-lang/cargo,eminence/cargo,tsurai/cargo,tsurai/cargo,nipunn1313/cargo,nipunn1313/cargo,tsurai/cargo,eminence/cargo,tshepang/cargo,tsurai/cargo