Auto merge of #5328 - dwijnand:doc-links-key, r=matklad
Auto merge of #5328 - dwijnand:doc-links-key, r=matklad

Add a reference to the links key in the manifest docs

Fixes #4975

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