Merge branch 'du/rev-parse-is-plumbing' into maint

Doc update. * du/rev-parse-is-plumbing: doc: move git-rev-parse from porcelain to plumbing

Junio C Hamano committed Nov 21, 2018 at 22:58 UTC 95500c8a0d252e70f32f6c7aedda204741bf5dfd

No changes.