Auto merge of #3758 - mbrubeck:docs, r=alexcrichton
authorbors <bors@rust-lang.org>
Thu, 23 Feb 2017 18:33:54 +0000 (18:33 +0000)
committerbors <bors@rust-lang.org>
Thu, 23 Feb 2017 18:33:54 +0000 (18:33 +0000)
Document that OUT_DIR is set during compilation for packages with build scripts

None


Trivial merge