Rollup merge of rust-lang#79627 - ehuss:update-cargo, r=ehuss

Update cargo

12 commits in bfca1cd22bf514d5f2b6c1089b0ded0ba7dfaa6e..63d0fe43449adcb316d34d98a982b597faca4178
2020-11-24 16:33:21 +0000 to 2020-12-02 01:44:30 +0000
- Add "--workspace" to update command (rust-lang/cargo#8725)
- Add an FAQ for "Why is my crate rebuilt?" (rust-lang/cargo#8927)
- Set docs.rs as the default extern-map for crates.io (rust-lang/cargo#8877)
- remove extra whitespace when running cargo -Z help (rust-lang/cargo#8924)
- Remove version from dev-dependencies to make it easier to publish. (rust-lang/cargo#8920)
- update dependency queue to consider cost for each node (rust-lang/cargo#8908)
- Fix some rustdoc warnings. (rust-lang/cargo#8911)
- Bump miow dependency to not invalidly assume memory layout (rust-lang/cargo#8909)
- Remove unnecessary trailing semicolons (rust-lang/cargo#8906)
- Fix custom_target_dependency test. (rust-lang/cargo#8907)
- fix: we don't ignore `version` for `git`/`path` deps now (rust-lang/cargo#8900)
- doc (book): add "Getting Started" subsection: "Essential Terminology" (rust-lang/cargo#8855)