Auto merge of #5580 - ehuss:doc-build-plan, r=alexcrichton
authorbors <bors@rust-lang.org>
Mon, 28 May 2018 02:11:09 +0000 (02:11 +0000)
committerbors <bors@rust-lang.org>
Mon, 28 May 2018 02:11:09 +0000 (02:11 +0000)
Document unstable --build-plan


Trivial merge