Auto merge of #6447 - ehuss:doc-name-authors, r=alexcrichton
Auto merge of #6447 - ehuss:doc-name-authors, r=alexcrichton

Document `name` and `authors` in [package]

I don't think we need to take a principled stand on the exact meaning of
"authors", so I left it somewhat vague. Also, it was made optional in #3682 so
the existing docs were a little wrong.

Closes #5934

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